In some PS5 games you may notice that the game has black bars around the corners (top, bottom, left, right). The image is smaller than the TV screen and isn’t scaled correctly (Game isn’t Fullscreen).
This is usually caused by a wrong Display Area in your PS5 Settings. Here’s how to easily fix this issue:
PS5 Settings > Screen and Video > Screen > Adjust Display Area > Adjust it until it fits your screen (no black bars)
When you’ve set the Display Area correctly, return to your game and it should now be fullscreen. If this doesn’t fix the issue, check the Game Settings (usually under Graphics) if the Display Area can be adjusted in-game. Some games use their own setting instead of your PS5 setting.