Steven Troughton-Smith:

If you want to pixel-peep on iOS or iPadOS, it also has the Zoom accessibility setting, and can be controlled via touch, keyboard, or trackpad. It works for display mirroring too, and has other options like a minimap and HUD (‘Zoom Controller’).

These settings are in Settings → Accessibility → Zoom. I prefer switching the Zoom Region from the default Window Zoom (which gives you large magnifier glass window to drag around the screen) to Full Screen Zoom, which is more like how zooming works on the Mac.

On iPadOS, you should go into the Keyboard Shortcuts panel (inside Accessibility → Zoom) and turn on Zoom with Scroll Wheel. This lets you zoom Mac-style, using the Control key, when you have a keyboard and trackpad/mouse connected.

(You can, of course, zoom on VisionOS too.)