Damage type invulnerability for an entity can be set with the following command:
/dmginvuln |entities| set |damage_type| |invulnerable|
/dmginvuln @a set fall true - sets fall damage immunity for all players
You can query damage type invulnerability with:
/dmginvuln |entities| get |damage_type|
/dmginvuln @e[type=creeper,limit=1, sort=nearest] get onFire - gets whether the closest creeper is invulnerable to fire or not
