Custom work (a Booking Request): Yes. Once you submit the Artists Booking Request form (tap Book Now on their profile), a chat opens with the Artist (tap Messages in the bottom navigation bar to find it). That's where you can talk through details, ask questions, and get on the same page before you pay the deposit request that Books your appointment.
A Wanna Do Design: Not beforehand. A Wanna Do is ready to Book as-is at its listed asking price, and the chat with the Artist opens after you Book.
Once your chat is open, it's where you and the Artist handle everything for your appointment, all in one place:
Finding a time that works
Discussing the design & procedure
Confirming placement
Aftercare instructions
You'll get notified when the Artist replies.