https://ringofbrodgar.com/wiki/Attributes#CharismaAffects your authority gain in conjunction with Intelligence.
Unless you need to maintain a large village claim alone, negilible.
Affects the maximum number of players allowed in your party.
Not sure if this is even a thing anymore.
Affects reward from quests.
From what I remember reading, this used to be really powerful but was heavily nerfed. Not sure if weight of CHA in reward generation was just generally gutted, or there's some kind of "breakpoint", after which raising Charisma gives little to no benefit in terms of questing.
Provides a bonus when feasting at a Bonfire.
This has been re-implemented:
viewtopic.php?f=39&t=48195&p=629364But apparently is a crapshoot if it actually works:
viewtopic.php?f=47&t=48295