Most websites these days use device type to determine which layout is displayed to the user. If you're on a desktop, you're shown the desktop layout. If you're on a mobile phone, you are shown the mobile layout. If, for whatever reason, one layout is not displaying properly, you can often "request" the other in your browser. This is how ArcGIS Dashboards works to switch between its desktop and mobile views, and I believe it's how Web AppBuilder worked as well.
Unfortunately, Experience Builder uses minimum screen size to determine the layout shown. This means if you have a window open on a desktop and resize it, it will switch to the tablet or mobile layout once it's small enough. According to a community post from 2023, a browser window with a width smaller than 992px will display the tablet/medium layout and a width smaller than 576px will display the mobile/small layout. It's a limitation that is especially frustrating when it comes to embedding Experience Builder apps into other websites, as the same break points apply to the iframe. And since there's still no option to design landscape layouts in tablet/mobile, the switch can be quite jarring.
It would be really nice to have the ability to choose how layouts are displayed (re: device type v. min. screen size). It may be possible to make edits to the JS in the Dev Edition, but that's beyond my capabilities at this time. I hope the Dev Team will consider a no-code solution to this problem! 😊
