[Parameter]
public bool FooterVisible { get; set; }

<DxButton Id="showDDbtton" Click="() => IsOpen = true">Show a drop-down window</DxButton>
<DxDropDown HeaderVisible="true"
    HeaderText="Header"
    FooterVisible="true"
    FooterCssClass="footer-style"
    FooterText="Footer"
    Width="max(25vw, 300px)"
    BodyText="Lorem ipsum dolor sit amet, consectetur adipiscing elit. Mauris sit amet metus vel
        nisi blandit tincidunt vel efficitur purus. Nunc nec turpis tempus, accumsan orci auctor,
        imperdiet mauris. Fusce id purus magna."
    @bind-IsOpen="@IsOpen"
    PositionTarget="#showDDbtton"
    PositionMode="DropDownPositionMode.Bottom">
</DxDropDown>

@code {
    bool IsOpen { get; set; } = false;
}

.footer-style {
    font-weight: bold;
}