So The knights of Ren in the sequal trilogy was mostly with kylo were they just his personal body guards or did they have a role like to hunt jedi or something?
The Knights of Ren were a group of dark side fanatics that loved everything dark side and chaos. They had no plans or schemes, other than serving chaos. Their leader Ren, is killed by Kylo, so they decide to follow him as he is the most chaotic person in the galaxy at that time.
It’s worth noting that the KoR in the Sequels may or may not have been directly descended from a group of Unknown Region marauders with origins that go back centuries prior. It’s heavily implied, and I personally believe, that the Sequel Era Knights were actually simply calling themselves by that name in order to take advantage of the probably mythical reputation of the “original” Knights of Ren.