If the parent and child will always have the same values in those fields, I would recommend not even creating them on the child. You can display fields from related records on view and forms. Here is an example:
This shows a list (view) of Cases which have a lookup to a customer record. The case itself does not have the customer's name or job title, but we can find that information because we have the relation to that record. This avoids data becoming "out of sync" between the two records, and reduces data storage needs.
If this doesn't solve your problem, there are some options to make it work. Probably a Power Automate flow that is triggered on record creation (child record being created) that will fetch the parent and use its info to populate the child. Then probably use Business Rules to lock the fields on the child record.
