Can I connect a 12V tape to a 10V power supply?

Everything will be fine. The tape will either not light up at all or will shine not as brightly as it should!

Plug in! And read more about how to work with different voltages in the articles:

https://my.electricianexp.com/en/kak-ponizit-postoyannoe-i-peremennoe-napryazhenie.html

https://my.electricianexp.com/en/kak-povysit-postoyannoe-i-peremennoe-napryazhenie.html