Create a bridged interface that acts as a trunk from the firewall and send all VLANs to that bridge. Connect a cable from each of the bridged ports to each of the switches. On the switches you can then specify which VLANs are allowed on the switchports connected to the firewall. You can delegate control to the switch in this case and your firewall rules and switchport assignments will help lock everything down.
If you have VLAN 1 (Management), VLAN 100 (Switch 1 VLAN), VLAN 200 (Switch 2 VLAN) then you just need to allow VLAN 1 and VLAN 100 on switch 1's connected switchport, and allow VLAN 1 and VLAN 200 on switch 2's connected switchport.
From that point everything else is controlled with switchport assignments to pass out the VLANs. If you need to add additional VLANs (300, 400, 500...) you create them, add them to the bridge, and enable them on the switchport(s). If you want to limit communication between the VLANs you create firewall rules to prevent this.
These can help make things much more clear in theory, but you would just adjust based on the switch manufacturer/model (unifi is used here)