What is the best way to set up aggregation from two channels?

Question

Mikrotik

could you tell me how to implement the scheme of two plates?
now in this scheme there is only one plate 192.168.120.1 and it is also a gateway and a dhcp server, the router 192.168.120.3 is configured as a bridge and simply strips wifi by
adding a second plate, the scheme will change and the router that distributes wifi will become a gateway with channel aggregation (bonding)
do you need two plates to allocate to a separate subnet, or to leave on the same addressing?
192.168.120.3 switch to router mode and configure dhcp on it?
how to do it better?

spoiler