IIT

For admission in NITs or IITs, they consider JEE Mains, JEE advanced and 12th percentage.

You can visit this link predictor for better results:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

No,
It's not possible for you to get admission in any of the NITs or IIITs or GFTIs. You have to go with low tier private colleges, use the college predictor tool to know in which colleges you can get admission.
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor.

If it is not above cut-off and under 5 thousand rank, it would not be possible to get any of the IITs.

With this score, your rank would range from 18k to 20k approximately. With this rank, it's not possible to get admission in any of the IITs. You can either admission in NITs based on your mains score.

Use the rank predictor tool to know the approximate rank. https://www.shiksha.com/b-tech/resources/jee-advanced-rank-predictor.

Yes,
Students who get a good rank in GATE entrance test can apply for Master degree in IITs.

Hi,
With 11000 rank in JEE Mains paper 2 2019 exam and a good score in your class 12th, you have less chances to secure admission in NITs and IITs.

Hi,
With 87.7 percentile in JEE Mains Paper 2 exam and a good score in your class 12th, you can surely secure admission in good colleges across the country. It would have been easier if you could have stated the state/ region, you are seeking to pursue your B.Arch programme. Check the link below to get a list of approved architecture colleges.
https://www.coa.gov.in/index1.php?lang=1&level=0&linkid=25&lid=26.