VLANs, FreeIPA, and AD trust on different subnets - how do the computers see each another?

Let me preface this by saying I am completely unfamiliar with VLAN tagging. I understand the basic concept, but I lack any sort of real-world experience.

I am looking into installing FreeIPA for a homelab. I have a simple 192.168.1.0/24 Active Directory setup with all hosts on same subnet.

Reading about FreeIPA, from what I understand it is best to have a separate domain name on a separate subnet, and create a trust relationship between AD and FreeIPA.

If I do this, how can the computers talk to one another? Aren't they isolated on separate subnets? Wouldn't this inhibit any sort of file sharing (e.g. samba, NFS, etc.)?

Has anyone who is using FreeIPA help me be less confused?

If possible, would love explanation to include (VLAN?) requirements for router (pfSense) and switches

Edit: Question in response to the first comment, then pfSense can configure the VLAN routing (e.g. "router on a stick") and allow routing as if on same subnet between separate subnets?

Then does switch have to be configured to allow VLAN tags (e.g. 10 for VLAN10 192.168.10.1 and 3 for VLAN20 192.168.20.1)?