docker-compose with multiple networks

I want to install NextCloud (https://hub.docker.com/_/nextcloud) via docker-compose.

After analyzing the docker-compose structure, I see that this image is composed of two services (app and db).

Currently, in a server, I have all docker based services running in a macvlan network so that they are visible to the rest of the devices in the network

How can I tweak the NextCloud docker-compose file in order to have the app and db containers communicate with themselves via the regular docker network, but have NextCloud service be exposed to the macvlan network?

Something like below:

--real network----
| 192.168.1.0/24 |
------------------
         |
---------|--docker network--------------
|  ---------                 --------  |
|  |  app  |--172.16.0.0/24--|  db  |  | 
|  ---------                 --------  |
----------------------------------------

So in theory I should be able to access NextCloud with the real network.

I've read that a reverse proxy could be the way to go but how can I set it up this way?