2019 27" imac Screen on Ventura 13.6.1

Sounds like you have zoomed into the screen. Check System Settings > Accessibility > Zoom and change according.

Hold down the Control key and run your finger up and down the mouse. If that changes the zoom you can run your finder down till you're back at normal. I use that to view small text.

Then if you don't want it turn it off as you'e already been instructed.

Just to add, I don't remember the default zoom shortcut but it is either command scroll or control scroll. Try both.