<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; }
    }
}