Yes, the IRS should find and credit the payment, provided that the payment exists or proof can be furnished should the IRS ask for it.  As long as the amended return is mailed by April 15, 2022, it is filed on time and any request for refund will be processed as long as the claim can be substantiated, even if the payment takes several months beyond April 15, 2022.

You cannot expect the IRS to find and credit the estimated payment omitted from your 1040. If you haven't yet filed then you should correct your return, and if you have filed then wait for the return to be accepted or rejected. If rejected you can then modify the return but if accepted you must then file an amended tax return.

I appreciate your thoughtful response to my query  There is one small factual error, however. I know, for certain that to claim a refund, the claim must be IN THE HANDS of the IRS, within three years of the filing date, WITHOUT EXTENSIONS. The postmark date does not matter.

If you haven't filed the original return yet I would just write in ink the estimated payment and change the amounts after it.  

For 2018 Estimated payments should be on schedule 5 line 66.  And go to 1040 line 17.  Here's schedule 5 if you don't have one.  https://www.irs.gov/pub/irs-prior/f1040s5--2018.pdf