I think there is a logical problem in your diagram.
You could do DHCP if you enabled a DHCP relay on the vlan 60 and also on vlan 204 interface on the FGT on Site2 and have it relay DNS Requests to the corresponding server on site1. That will work because DHCP is basically UDP broadcasting.
However you will not be able to route traffic because you have the same subnets on both sides at least in VLAN 204.
This works between switches but not over a vpn.
So I would recommend to have the DHCP Servers on SIte1 to have a pool for SIte2 that has a different subnet (Vlan 60 seems to be class B anyways already, 204 on Site1 might need a secondary IP on the vlan interface on site1 FGT) and also configure it to hand the FGT on site1 as gateway. Then the FGT on Site2 needs the DHCP relays and a route back to those new subnets over the S2S Tunnel.
"It is a mistake to think you can solve any major problems just with potatoes." - Douglas Adams