If you are referring to a Form 1099 MISC, you might be able to make an adjustment under Other Expenses with an explanation.
Generally, you should not change any amount reported from a 1099 form, like Form 1099-R or 1099-MISC. Since IRS is also receiving a copy of the form, by changing the amount would create a discrepancy between your tax return and the actual tax form. the IRS could question and request an explanation and an amended return which might impose any interest or penalty for the taxes owed.
[Edited 1/22/2021 3:20PM]
What you should do is enter all the 1099s and then make an entry on schedule C line 27a Other Expenses for the amount you received in the next year and say like Income not received until next year. And be sure to enter it on your next year's return as General Income not received on a 1099Misc.
I have the same problem, but the 1099-NEC actually overstates revenue because it include payments made in January 2020 for December 2019 invoices. So I already reported that amount in my 2019 taxes. The overstatement is not money to report in 2021, but has already been reported.