about all Olympiad for class 12 presently ( in 12 on 29.01.2022) or 12th passed students .
Hi there,
Some of olympiad for class 12th students are following:
National level science talent search exam.
Kishore Vaigyanik Protsahan yojana.( for science students)
IOEL ( International Olympiad of English language)
INO ( Indian national olympiad)
National science olympiad
For more details follow this link: https://www.google.com/amp/s/school.careers360.com/articles/scholarships-in-india/amp
Hope it helps you
Good luck!