Looking for an offline AI

So, I have been using chatGpt and other popular Ai agents since their start and idk much about these other than simply typing and getting the thing I need but the problem is These AIs need Internet.

So I learnt about something called an offline AI which doesn't require an internet and I was curious if I could use it in my Computer Practicals.

So the things I need in it are:

*Can be stored in a pendrive

*plug and play it

*No-Sign in required after putting it in the pendrive (so same thing as point 2)

*Easy to use if possible

Note:

I need it only for writing an essay.

The School computers are sh!t (like i3 and igpu) so I need something light weight