Hello aspirant,

If you want to pursue your BArch from IIT then you have to clear JEE main paper 1 as paper 2 is meant only for admission in NIT's and IITs and other colleges so if you have cleared the cutoff criteria for paper 1 and percentiles criteria then only you can sit for  advanced otherwise you can not take advanced by clearing paper 2.

Hope this helps

If any queries feel free to ask

All the best!!

Regards.