I’m currently traveling, and I happened to have an iPad in my backpack. I endeavoured to use it as a second screen for my Mac, and found surprising the low-quality of search results (although, the more mainstream a technology, the worst the search results). Hopefully this can help people with the same need.

Some results will tell you it’s possible only on M1+, but it’s not true. The iPad in question is a 9th generation, so not an M1, and it works. You need the iPad and a cable to connect it to your Mac. There’s certainly a minimum iOS/macOS level, I’ll let you find it.

Just click on that button, and your screen will appear on your iPad.

However, by default the iPad is showing black bars on left and bottom of the screen.

They’re supposed to add features, which I think are largely redundant. Given that the iPad screen already has little real-estate, I think it’s worth reclaiming it. The option is un-natural to find. It’s on your Mac, not on your iPad, and it’s in the toolbar. Click on the screen mirroring icon in the tray (which on my Mac showed up after I started the screen mirroring), then check both “hide sidebar” and “hide touchbar”.

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That’s it, now you’ve got the full screen of your iPad usable as a second screen.