I find ESO very solo friendly. The game is beautiful and, for the first time in TES history, staves are good weapons rendering playing as a pure mage perfectly effective. Though I consider being multiplayer a drawback, the sheer mass and scale of the game (which dwarfs TES IV and V combined) means by the time you explore everything, you'll have forgotten parts and they will seem new again. Almost a limitless supply of play, repeatable quests, things to do. There is player vs player for those who enjoy that but it is never forced upon you and is not a large part of the game. Buffy spends 95% of her time playing solo and completely eschews player vs player.
Anything about your character can be changed except their class. You can have multiple characters. Character creation is very good.
Assuming you are going to play on PC, you only have two servers: PC NA (PC, North America) or PC EU (PC, Europe). You cannot change servers once you commit unless you want to create another account. Chorrol has our own small guild active on both servers. Mostly we just get together to socialize or maybe run a dungeon or such once a month.
The game is quite complex and can overwhelm at first. It also (being multiplayer) is a dynamic and changing world so leaving the game for a few months and coming back requires plenty of catchup on what has changed.
I found UESP wiki a fantastic source of info when I played TES IV and V and such is happily the case with ESO as well.
https://en.uesp.net/wiki/Online:OnlineThe game is free to play and you should start that way to check it out. If you fall in love with the game, you will likely want to pay a subscription for ESO+. Costs 8-10 US$ a month depending on how long you subscribe at a time and the perks are well worth it if you play regularly.