Edit
I should have searched better before posting, but I didn't know exactly what words to use. Anyway, I searched for 'Notification pop' and found my answer. Settings > Advanced Features > Smart Pop-up view then unclick Chomp.

I have a Samsung Note 10 Plus. For some reason when I get a message an icon pops up in the middle of the screen instead of the action bar or pull down bar at the top of the screen. Then when I click on it, a tiny little window opens up. I prefer just a notification at the top of the phone where the clock and everything else is, and when I open the message I want full screen, or the full app, not a teeny tiny little pop up screen that requires an extra action to maximize.