If you downloaded your 2020 tax return as a PDF to include all worksheets, the 5 digit self-selected PIN you used on the 2022 tax return will be on the Federal Information Worksheet on page 3 at the bottom of the page.
You are not required to use the same 5 digit pin you used on the 2022 return for the 2023 tax return. You can choose to use any 5 digit self-select pin. What is required to e-file is the 2022 AGI that was on your 2022 federal tax return, Form 1040 Line 11. The 2022 AGI is used for your electronic signature when e-filing.