<TelerikStepper Linear="true" ValueChanged="@HandleValueChanged">
    <StepperSteps>
        @for (int i = 0; i < IsValidArray.Length; i++)
        {
            <StepperStep Valid="@IsValidArray[i]"></StepperStep>
        }
    </StepperSteps>
</TelerikStepper>

@code {
    bool?[] IsValidArray = [null, null, null, null];

    public void HandleValueChanged(int index)
    {
        for (int i = 0; i < IsValidArray.Length; i++)
        {
            IsValidArray[i] = index > i ? true : null;
        }
    }
}