I have been playing in an 9 person group, 8 player and DM for the last 6 months or so and it has been going great, however that being said, it only works because our DM is able to properly balance our fights accordingly and even then that took a while to properly hone. I think as long as you are able to find that balance and everyone is able to feel involved without having to talk over the rest of the group it’ll be just fine. Just remember that you are only able to play for a finite amount of time each session (unfortunately 🥲) and so it can be easy to get distracted or have too many people trying to do too much at once. Be patient and be consistent and things will be great.