Yes you can apply for Upsc 2021. The age limit criteria for UPSC exam is 21-32 years of age for general category and 3 years relaxation for OBC category. So you can apply for UPSC 2021. The other eligibility criteria are that you must be a citizen of INDIA, and you must hold a graduation degree in some recognized field.

Refer to the following website for more detailed information -

https://competition.careers360.com/articles/upsc-ias-eligibility-criteria

Best wishes. Thank you.