Been playing this for the last few years. Helped me get through lockdown!
It's been around for long enough that there is absolutely loads of content. I love that there are several different ways to play, too. I love housing and decorating, but there's casual questing, end game content, PVP, crafting... It's fun!
I don't know if we're permitted to post links that that here, so I won't. But if you go to the Epic Games store, it's free through 27 July.
I know it shifted from a subscription model to a paid DLC one. Do you actually need to buy some DLCs to get an enjoyable experience out of this? Do you only need the endgame stuff once you get there, like buying the latest WoW expansion? How does this model actually work for chill players?
You can do probably 60-70% of the game just with base version. You won't be hamstrung by missing meta sets or content. Even then, DLC sets that can be crafted can still be obtained by having someone else craft the for you, or by having access to tables via a guildmate (like 95% sure it works that way, if not, you just need the 3rd party crafter). You'll obviously miss the new zones, dungeons, trials, and skill lines, but you'll still get over a hundred of hours of content.
You can absolutely play this casually. The base game stuff is pretty easy in comparison to how it was, with power creep and such, but it's, at worst, a good, long introduction to the game systems to better gauge your future interest.
If you subscribe and get ESO+, you get '...Access to all DLC game packs available in the Crown Store for the duration of membership'. That does not include the latest chapter; right now that's Necrom. There's a new one each year, so you'll be able to play Necrom next year with a membership if you don't want to buy it outright.
They do a good job of making the membership very appealing, I have to say. Increased bank space, double the slots for furnishings in your houses, and a bottomless crafting bag, for ex. But they are not obnoxious about it like, say, Neverwinter Nights is.