If you want to enable the setting, it’s under
Settings > Profile > Advanced Settings > Mark this account as a cat
(wording/location may vary if you’re using a misskey fork but it should be under the profile settings somewhere)
This will give your icon cat ears in public timelines and any text you write will be converted to catspeak. Works better in Japanese, which is the language it was designed for, but in English words like “now” get converted to “meow” for example.
It was heavily criticized due to the severe drop in animation quality after the first episode. It’s like they spent 95% of the budget in episode 1, which got everybody hyped (and it is legitimately good), and then left the rest of the budget to pay a couple of overworked interns to haphazardly put together the rest of the animation.
The events of the story are all there, and the art style is the closest you can probably get to the original, but it does fail to capture a lot of the magic of the manga due to shoddy animation. I wouldn’t recommend it, personally.