how do i auto relate tasks to Person Accounts?

Hello Ryan,

You can create a lightning flow to relate the tasks to person accounts as Process builder and workflow features are getting retired soon.

If you are new to lightning flow then this video will give you a basic idea of how it will work in your business use case - https://www.youtube.com/watch?v=37KrxoxrSZ0

Also, check the considerations for Using Person Accounts - https://help.salesforce.com/s/articleView?id=sf.account_person_behavior.htm&type=5

Hope this helps. Thank you