I didn't file my Return on time April 15. Can I still file them?

[Rainman12]

Yes - you can e-file to 15 October, paper file up to 2022.

[mesquitebean]

If you are due a Federal refund, there is no penalty for a late Federal return.   State rules may vary.

But if you have taxes due (owed), and did not request an extension, then you should file and pay as soon as possible.  When taxes are owed, there can be a late filing penalty and a late payment penalty plus interest, which will keep growing until paid.