Unraid has the WireGuard VPN server built in and as long as the client machine you use can run a WireGuard client (e.g. Windows, iOS, iPadOS, Android) then you can use that to securely connect and operate as if you were connected directly to your local LAN. There are other similar options available but since WireGuard is built in I find that the most convenient.
Whatever you do you must not try and expose an Unraid server to the internet directly by putting it into your router's DMZ as it is not hardened against the attacks you would then get.