Depends on what are you talking about "extras":
If it's side play during a massage (e.g oral and/or jo) it should be part of the 'Erotic' massage rate. You should've asked if they provide an erotic massage.
If you're wanting full on escort/sex, you ask them if they provide "full service". Nobody should be getting offended by being asked this, especially if it's someone you met on say rentmasseur.
I can share that I had an awful interaction with a massage guy who had a great massage technique and we would have some side play to finish. He was charging escort rates but I didn't mind much because it was a good massage/side play and I'd see him every weekend for about 2 months UNTIL one day he didn't engage on the erotic side nor he say anything about why was it missing so I paid and left. A week later he asked me if I wanted to book and I said that I would, but for his rate I would always expect erotic play. He then went off on me saying that if he wasn't feeling it he wasn't feeling it and that I shouldn't be coercing him to do any thing, because it's his body and what not. I said it wasn't gonna work for me because at that rate I'm not going to be for 40 minutes on that table wondering if it's gonna happen or not that time, the whole point is for me to relax. I thanked him and he blocked me 🤷♂️
If you're a provider and you're not feeling it I totally get it, you should set your ad to 'not available' until you're feeling it, otherwise is just scamming people.