MacOS: How to share screen with a relative to give them techncial support?

On MacOS, is there anyway you can share the screen of a person who is living far away (i.e. on a different wifi network), to give them techncial support?

I googled it, as I see that it is possible to do it via the "Ask to Share Screen" option of Messages. However, when I try this option, it is greyed out.

I see a lot of other options such as using System Preferences > Sharing > Screen sharing, but I think these require both Macs to be on the same network and can't be done via the internet.

System: Mac OS 12.6.9. However, I'd like to know if it's possible on a variety of Mac OS versions (as different relatives can have different versions).