This example shows how to change the viewer options. First, load scripts:
@using Stimulsoft.Base
@using Stimulsoft.Report
@using Stimulsoft.Report.Blazor
@using Stimulsoft.Report.Web
Next, add report viewer:
<!--Report Viewer-->
<StiBlazorViewer Report="@Report" Options="@Options" 
                 Width="650" Height="650" 
                 Theme="StiViewerTheme.Office2013WhiteCarmine" />
After that, initialize options object:
@code
{
    //Report object to use in Viewer
    private StiReport Report;
    //Viewer options object
    private StiBlazorViewerOptions Options;
    protected override void OnInitialized()
    {
        base.OnInitialized();
        //Init options object
        this.Options = new StiBlazorViewerOptions();
...
Finally, set some options, create empty report object and load report template:
...
		//Set some options
      	this.Options.Appearance.FullScreenMode = true;
      	this.Options.Appearance.ScrollbarsMode = true;
        this.Options.Toolbar.ShowOpenButton = false;
        this.Options.Toolbar.DisplayMode = StiToolbarDisplayMode.Separated;
        //Create empty report object
        this.Report = new StiReport();
        //Load report template
        this.Report.Load("Reports/TwoSimpleLists.mrt");
    }
}
In the screenshot below you can see the result of the sample code: