Migration to blocks - Clarification/issues moving from 3.6 to 3.8 (or latest)?

I see, I am on 3.6.6.2 but don’t see a migration script, would you mind pointing me in the right direction? Is it something built in to core or do I need to use this custom script from here? Bulk Builder field to Kirby Block 3.7 conversion - #8 by mactux