Implement table-level hints:

MERGE, NO_MERGE 

DERIVED_CONDITION_PUSHDOWN, NO_DERIVED_CONDITION_PUSHDOWN

in the same way they're done in MySQL 8. See MySQL docs at:
https://dev.mysql.com/doc/refman/8.4/en/derived-condition-pushdown-optimization.html
https://dev.mysql.com/doc/refman/8.4/en/optimizer-hints.html#optimizer-hints-table-level

The logic for enabling the hints is expected to be very basic - hook at the same place where the check for optimizer_switch is, override the optimizer_switch setting.

The code to base on is MDEV-35504, look at other similar level hints and copy the approach.