A Google search (ai response, so take it with a grain of salt) suggested a 5 person party could take a dragon with 136 hp and 18 a at levels 8-9 comfortably. 7-8 would be hard, 5-6 would be very difficult but possible. Depends on the DM too.
Note I don’t play much 5e, and my experience in TTRPGs outside a few single session stuff is mostly one Pathfinder 2e campaign currently at level 6.





I may be dating myself as an older weeb with this reference, but Osaka from Azumanga was not what you’d consider intelligent, but she got riddles instantly because she just thought weird.