short cut to magnification

Press Control & Option at the same time to activate a magnifier window:

You will need to hold both keys down to use this feature.

The magnifier screen can be repositioned with the cursor.

Using a trackpad the zoom level can be adjusted with two finger contact moving up and down on the pad.

[I have no idea how this would work with a mouse, as I do not have one]

Hi, welcome to the Apple Users Community.

You have many variations of this

Some windows - can be adjusted using System Preferences>Displays and using the Scaled option

Desktop Finder windows - can be adjusted in the View Menu (⌘J)

Browser windows - command + (⌘+) will zoom in and (⌘-) to zoom out

If you could be a little more specific, it would help us to help you.

Best of luck