Your battle party is maxed out at 3 but can swapped on the fly mid battle. Battles work with each party member having their own set of skills and a type of damage which some enemies are weak against, each party member also has a field skill allowing them to interact with the world to solve puzzles and further that all important map exploration.
One thing I struggled to adjust to is that you cannot change the camera angle, only zoom in and out. It didn’t affect the gameplay too much, except for when I’d forget and try to turn the camera to look around the corner of something only for the camera to instead zoom in on my party.
Overall, I really enjoyed my revisit to the Ys series and it was refreshing to see how much it has progressed, it’s reaffirmed why I got addicted to this series in the first place and I can't wait for the next title.