Xenoblade Chronicles 3 is set in the world of Aionios, which is notable for its 2 major nations of Keves and Agnus - who constantly war with one another. Characters from Keves and Agnus only have 10 year life spans dubbed "terms".
In Xenoblade Chronicles 3, you control 6 primary characters, 3 from Keves, and 3 from Agnus, who become unlikely allies and friends, who will end up fighting together to discover the truth of the world of Xenoblade Chronicles 3. In order to fight, each character starts with a primary class with its own set of arts to use in fightings - however, can switch classes and arts in-between fighting to level up and learn all new master arts that can be equipped regardless of class.
Some of the classes available included Swordfighter, Zephyr, Medic Gunner, Tactician, Heavy Guard, Ogre, Guardian Commander, Incursor, and War Medic.
Importantly, each of the main characters has another character they'll be able to interlink with. This fuses the two characters you choose together into a mech-like form called an Ouroboros for a limited set amount time. These Ouroboros also have special arts, however not constrained by the same limits as the characters on their own.
Xenoblade Chronicles 3 releases July 29, 2022, with additional content releasing later this year, and into next year through a Xenoblade Chronicles 3 Expansion Pass for an additional cost.