Hello student yes you can appear in NEET at 21 or 22 year of age as there's no upper age limit in NEET entrance examination. You ne need to full fill the eligibility criteria.

Eligibility - Candidates must passed or appearing class 12 with physics chemistry and biology with minimum 50 percent marks from a recognized.

Minimum 17 year old.

For more updates refer to the link mentioned below - https://medicine.careers360.com/articles/neet-eligibility-criteria/amp

Feel free to comment if you have any doubt

Good luck