Signature Width: <TelerikNumericTextBox @bind-Value="@NumValue" Width="120px" />

<TelerikButton OnClick="@ResizeSignature">Resize Signature</TelerikButton>

<br /><br />

@if (ShowSignature)
{
    <TelerikSignature @bind-Value="@SignatureValue"
                      Width="@( $"{SignWidth}px" )"
                      Height="@( $"{SignHeight}px" )"
                      Maximizable="false">
    </TelerikSignature>
}

@code {
    private string SignatureValue { get; set; }

    private int NumValue { get; set; } = 300;

    private int SignWidth { get; set; }
    private int SignHeight { get; set; }

    private bool ShowSignature { get; set; } = true;

    async Task ResizeSignature()
    {
        ShowSignature = false;

        SignWidth = SignHeight = NumValue;

        await Task.Delay(1);

        ShowSignature = true;
    }

    protected override void OnInitialized()
    {
        SignWidth = SignHeight = NumValue;

        base.OnInitialized();
    }
}