Experiences are always good. Couples massage, dinner at a nice restaurant, go to a theatre, go hiking somewhere special, go to a class together for an activity you can do as a couple, buy a game you can play together, hire a cleaner to come clean your house while you go out for a beach day together, go to a wine tasting, do an escape room, take a tour of somewhere you've never visited, etc. The most important aspect of the anniversary gift imo is that it should involve spending time together.