Dorico 3.5.12?

I have Dorico 3.5.10. I run Mac Mojave 10.14. Can I update to Dorico 3.5.10? If so, how?

Yes, you can. Simply run the Steinberg Download Assistant, get the 3.5.12 updater and let it run.

Or download the updater directly from Steinberg > Support > Downloads > Dorico.