Do you mean physical computer keyboards? If you’re on a Windows or Linux machine I’m pretty sure there’s an alt code for it, but I never remember what any of those are. On a Mac computer you can hit option+0 to get the ° symbol.

On Apple devices with on-screen keyboards you just long-press zero to get the the ° symbol, that’s how I’m typing right now. I’d assume android has the same feature but idk I haven’t used an Android enough to the point I needed to type ° in 6 years or so.

To the other persons point, this is all on American English keyboards, but I don’t see why there would be any difference between that and a UK English keyboard, or any other keyboard language with a Latin-script alphabet for that matter.