Can have more than 1 item up

Hello,

Another option would be using Split View to have both apps side by side in fullscreen.

Use two Mac apps side by side in Split View - Apple Support

"macOS Catalina or later

1. Hold your pointer over the full-screen button  in the upper-left corner of a window. Or click and hold the button.
2. Choose ”Tile Window to Left of Screen” or ”Tile Window to Right of Screen” from the menu. The window then fills that side of the screen.
3. Then click a window on the other side of the screen to begin using both windows side by side."

I hope this helps.

You are welcome.

Personally I love this feature when needing to take notes about information from a different app. It utilizes Spaces so you can have a space of Microsoft Word split with Safari while having another space for recording references, background music, or whatever else could be useful to you.

Use Mission Control on your Mac - Apple Support

"When you have multiple spaces, you can switch between them by clicking the thumbnails the top of the Mission Control window. Or use these methods, which work even when you're not in Mission Control:

• Swipe left or right with three or four fingers on your trackpad, or swipe left or right with two fingers on your Magic Mouse.
• Press Control–Right Arrow or Control–Left Arrow on your keyboard."

Please see: Use Stage Manager to organize apps and windows on Mac - Apple Support

Try turning off Stage Manager in the menu bar. What you are seeing is the normal procedure for Stage Manager.