If your scenario is more complex, please provide a demo.
<TelerikTabStrip @bind-ActiveTabIndex="@ActiveTab"Height="600px">
<TabStripTabTitle="Tab 1"><divstyle="height:100%;background:#ffc;">This DIV will expand to fill the TabStrip</div></TabStripTab><TabStripTabTitle="Tab 2">
Content 2
</TabStripTab><TabStripTabTitle="Tab 3">
Content 3
</TabStripTab>
</TelerikTabStrip>
@code {
private int ActiveTab { get; set; }
}