I have to admit, I’m a bit confused.

I have dns records already in my domain provider pointing to a tailscale ip

I want to know what I have to do to get minecraft.example.com to resolve interenally.

Since your domain resolves to an internal private Tailscale IP and your question is how to access using the domain, locally…. I feel like there’s an error in your architecture here. Wouldn’t any device that is on your Tailscale private network already have access using the domain? If by “resolve internally” you mean hosts on your LAN, not connected to Tailscale scale? How would that be possible if it resolves to a Tailscale IP. If you have control of your DNS on your LAN, you could simply add an override and point it to the LAN address of the Minecraft server.