Is it possible to choose one window template for each screen device view in ArcGIS Experience Builder?

Answer

No, it is not possible to choose one window template for each screen device (large, medium, or small) view in ArcGIS Experience Builder. Only one window template can be selected, but using only one template disrupts content visibility that may be affected by the screen size differences.

1. Open the ArcGIS Experience Builder experience and click Page to open the Page panel.
2. Click the Window tab, and select the window to be customized.
3. On the builder toolbar, click the Edit your page for medium screen devices button to refine the layout for medium screen devices.

Note: 
Clicking the Edit your page for medium screen devices or Edit your page for small screen devices button displays the window view in the medium-screen devices mode. The option to set the layout to Custom is in this view mode.

4. Click the Custom button next to the window layout.

5. When the Are you sure you want to enable it? dialog box is prompted, click OK.

6. On the window, drag the edges of a widget to resize the widget, or drag and drop a widget to a suitable position to rearrange the widget position.
7. Repeat Step 6 to resize and rearrange the widget position for all the other widgets in the window.
8. On the builder toolbar, click the Edit your page for small screen devices button to refine the layout for small screen devices.

9. Repeat Steps 4 through 7 to resize and rearrange the widgets in small-screen size mode.
10. Click Save to save the experience.

The images below show the window views for the large, medium, and small screen devices.