For example, TANCET, MHTCET, KCET, APICET, TSICET
College- Anna University, College of engineering Pune.
I'm confused because for example IPU, they conduct their own CET. And the tests which I have mentioned above, will the colleges conduct those or I have to separately apply for writing them? Do I just need to fill application form of Colleges only?

chetanya Hi,
You have mentioned about State Level Entrance exams conducted in different States by the respective State Authorities. Exams listed below are conducted by University of that State on behalf of the State Council of Higher Education
TANCET by Anna University on behalf of Directorate of Technical Education, Tamil Nadu - Official Website Link: https://www.annauniv.edu/

KCET by Karnataka Education Authority - Offical Website Link - http://kea.kar.nic.in/

TSICET by Kakatiya University, Warangal on behalf of Telangana State Council for Higher Education - Offical Website link: https://tsicet.nic.in/

MHT CET by Maharashtra State Board of Secondary and Higher Secondary Education - Official website: https://cetcell.mahacet.org/

AP ICET by Sri Venkateswara University on behalf of
Andhra Pradesh Council for Higher Education - Offical Website Link: https://sche.ap.gov.in/APSCHEHome.aspx

To apply for any of the exam listed above you need to visit their official website and can get more information about the exam on their official websites mentioned above.

Hope this helps you.
Thank you!!