It is still better to file an extension as it is not an extension to pay the amount due just an extension to file. The failure to pay penalty is a percentage of the amount due per month and adds up quickly. Best to overestimate what you owe and pay it by 4/18/2022. If you are getting a refund, don't worry about it.
If you file an extension, you have six months to complete your tax return. There will be penalties and interests if you owe. The extension is to file your return, but the payment is due now. You need to estimate what you would owe when filing an extension.
To file Form 4868 to request an extension on time to file your tax return, select your situation:
Keep in mind: An extension doesn't give you extra time to pay your taxes, but it'll keep you from getting a late filing penalty. (You'll still owe interest if you pay after the deadline.)