Is Groupable: @IsGroupable
<TelerikButton OnClick="@ToggleGroupable">Toggle Groupable</TelerikButton>

@if (isGridVisible)
{
    <TelerikGrid Data=@GridData @ref="@GridRef" Groupable="@IsGroupable" Pageable="true" Height="400px">
        <GridColumns>
            <GridColumn Field=@nameof(Employee.Name) Groupable="false" />
            <GridColumn Field=@nameof(Employee.Team) Title="Team" />
            <GridColumn Field=@nameof(Employee.IsOnLeave) Title="On Vacation" />
        </GridColumns>
    </TelerikGrid>
}

@code {
    bool IsGroupable { get; set; }
    bool isGridVisible { get; set; } = true;
    TelerikGrid<Employee> GridRef { get; set; }
    async Task ToggleGroupable()
    {
        //save state (sorting, paging,...) - it will be lost when we hide the grid
        var state = GridRef.GetState();

        //hide the grid so it can later re-initialize with the new groupable setting
        isGridVisible = false;
        await InvokeAsync(StateHasChanged);
        await Task.Delay(20);
        IsGroupable = !IsGroupable;
        isGridVisible = true;

        //afte the grid re-initialized and rendered with the new setting, restore its state
        await InvokeAsync(StateHasChanged);
        await Task.Delay(20);
        await GridRef.SetState(state);
    }


    public List<Employee> GridData { get; set; }

    protected override void OnInitialized()
    {
        GridData = new List<Employee>();
        var rand = new Random();
        for (int i = 0; i < 15; i++)
        {
            GridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3,
                IsOnLeave = i % 2 == 0
            });
        }
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
        public bool IsOnLeave { get; set; }
    }
}

<GridColumn Field="@nameof(SalesOrderLineItem.Quantity)">
    <HeaderTemplate>
        <span title="Order Quantity">Order Quantity</span>
    </HeaderTemplate>
</GridColumn>

<TelerikButton OnClick="@CurrentPage">Current Page</TelerikButton>
<TelerikButton OnClick="@AllPages">All Pages</TelerikButton>

<TelerikGrid Data="@GridData"
             @ref="@GridRef"
             Pageable="true"
             Sortable="true"
             Resizable="true"
             Reorderable="true"
             FilterMode="@GridFilterMode.FilterRow"
             Groupable="true">



    <GridExport>
        <GridExcelExport FileName="telerik-grid-export" AllPages="@ExportAllPages" />
    </GridExport>

    <GridColumns>
        <GridColumn Field="@nameof(SampleData.ProductId)" Title="ID" Width="100px" />
        <GridColumn Field="@nameof(SampleData.ProductName)" Title="Product Name" Width="300px" />
        <GridColumn Field="@nameof(SampleData.UnitsInStock)" Title="In stock" Width="100px" />
        <GridColumn Field="@nameof(SampleData.Price)" Title="Unit Price" Width="200px" />
        <GridColumn Field="@nameof(SampleData.Discontinued)" Title="Discontinued" Width="100px" />
        <GridColumn Field="@nameof(SampleData.FirstReleaseDate)" Title="Release Date" Width="300px" />
    </GridColumns>
</TelerikGrid>

@code {
    async Task AllPages()
    {
        ExportAllPages = true;

        await Task.Delay(20); // allow the component to rerender with the new parameter

        await GridRef.SaveAsCsvFileAsync();

        //await GridRef.SaveAsExcelFileAsync(); // this works
    }

    async Task CurrentPage()
    {
        ExportAllPages = false;

        await Task.Delay(20); // allow the component to rerender with the new parameter

        await GridRef.SaveAsCsvFileAsync();

        //await GridRef.SaveAsExcelFileAsync(); // this works
    }


    private TelerikGrid<SampleData> GridRef { get; set; }


    List<SampleData> GridData { get; set; }
    bool ExportAllPages { get; set; }

    protected override void OnInitialized()
    {
        GridData = Enumerable.Range(1, 100).Select(x => new SampleData
        {
            ProductId = x,
            ProductName = $"Product {x}",
            UnitsInStock = x * 2,
            Price = 3.14159m * x,
            Discontinued = x % 4 == 0,
            FirstReleaseDate = DateTime.Now.AddDays(-x)
        }).ToList();
    }

    public class SampleData
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public int UnitsInStock { get; set; }
        public decimal Price { get; set; }
        public bool Discontinued { get; set; }
        public DateTime FirstReleaseDate { get; set; }
    }
}

<style>
    .custom-searchbox-width .k-grid-search {
        width: 50%;
    }
</style>

<TelerikGrid Data=@GridData Pageable="true" Height="400px" Class="custom-searchbox-width">
    <GridToolBar>
        <span class="k-toolbar-spacer"></span> @* add this spacer to keep the searchbox on the right *@
        <GridSearchBox />
    </GridToolBar>
    <GridColumns>
        <GridColumn Field="@(nameof(Employee.EmployeeId))" />
        <GridColumn Field=@nameof(Employee.Name) />
        <GridColumn Field=@nameof(Employee.Team) Title="Team" />
        <GridColumn Field=@nameof(Employee.IsOnLeave) Title="On Vacation" />
    </GridColumns>
</TelerikGrid>

@code {
    public List<Employee> GridData { get; set; }

    protected override void OnInitialized()
    {
        GridData = new List<Employee>();
        var rand = new Random();
        for (int i = 0; i < 15; i++)
        {
            GridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3,
                IsOnLeave = i % 2 == 0
            });
        }
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
        public bool IsOnLeave { get; set; }
    }
}

<TelerikGrid FilterMode="Telerik.Blazor.GridFilterMode.FilterRow"
             Data="@GridData"
             Resizable="true">
    <DetailTemplate>
        detail template
    </DetailTemplate>
    <GridColumns>
        <GridColumn Field="Id" />
        <GridColumn Field="Id" Title="Resize Me First" />
        <GridColumn Field="Id" Title="Resize Me First" />
    </GridColumns>
</TelerikGrid>

@code {
    List<GridModel> GridData { get; set; }

    protected override void OnInitialized()
    {
        List<GridModel> data = new List<GridModel>();

        for (int i = 1; i <= 3; i++)
        {
            data.Add(new GridModel { Id = i });
        }

        GridData = data;
    }

    public class GridModel
    {
        public int Id { get; set; }
    }
}