Hello,
USMLE is still in the process of completing their 2021 exams so as of now there is some time left, but do keep checking their website for further updates.
Step 1 ,2 and 3 are computer based tests which are administered at their centres worldwide.
Do check out the 2022 bulletin on their website:
https://www.usmle.org/bulletin/
All the best!
Eligibility | Application | Result | Dates | FAQs
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile