Deductions & credits

Thank you all for answering my question. I'm glad I didn't use my 2019 income & waited for a reply. Yes, I would have loved to already had filed my 2019, but due to not having all the proper documentation to file yet (Ex. All my receipts, etc.), has stopped me from yet filing. So once I can get back to my home state, get the correct documentation to make sure my numbers are correct, then I can file 2019. 

To be clear, can I later amend my 2020 taxes so I can use my 2019 income that is much higher, in turn a bigger refund? I can really use the refund money at the moment, so if I don't have to wait to file I don't want to.