Hi there,
Hope you are doing well.
12,000 rank is a little high in case of JEE Mains paper 2.
Unfortunately, you won't be able to get into any of NITs or GFTIs or SPAs since most of them have a closing rank of at most 7,000-8,000 for General Category, but you can try for private colleges.
Hope it would help.
Thank You.
You can check detailed cutoffs here:-
https://engineering.careers360.com/articles/jee-main-cutoff-for-b-arch-b-planning