Migrating MySQL 8.0.20 database to AWS Aurora
The biggest potential problems with going backward from 8.0:

CTEs
Windowing functions
new COLLATIONs
Various minor syntax changes that are best found by trying the transfer.

If you are not using those, a mysqldump might produce a file that can be read by 5.6 or 5.7.  Try it.  Come back with specifics if that fails.