How to change FRS to DFRS in an Activedirectory domain ina a forest?

[Nike98]

Hello,
I'm going to replace all domain controllers in an ActiveDirectory domain. Current DCs are very old and using FRS for replication.
When I replace the servers, I would like to change the replication method from FRS to DFRS. Are there any impact to other AD domains in the same forest?
I think that this change’s effect is closed in an AD domain. I dug MS site, but could not found information about this.

Current environment:
-Some AD domains in a forest
-The forest and domains are working as function level 2003
- Old domain controllers are Windows 2008, new ones are Windows 2019

[#2]

The Domain functional level needs to be 2008, so if a domain in your forest had that level.. Then you can switch to DFSR for that domain

[#3]

Thank you for your response, Harm!
I’m very happy to hear your advice! If I change the domain function level, do I need to change any settings on other domains and a forest?

[#4]

No, you only have to change the Domain Functional level in the domain that you want to use DFSR.

[#5]

This this help?