Vlan and Trunk

[Itaid]

Best Way to configure Fortinet 60f as per given topology. In this topology every Lan5 -Lan 7 is connected to L2 manageable switches. All client devices are connected through these L2 switches.  What will be the best possible configuration?

[Toshi_Esumi]

In your situation, you don't have to/can't utilize VLAN switch specific feature(native vlan & trunk port, almost no practical use cases) it's the same as hard-switch. Only thing you need to be aware is your can not use VLAN 1 (reserved) on the FGT. Instead you need to utilize the parent/non-tagged interface, which is by default "internal" for LAN port 1-5. All VLAN tagged sub-interfaces you create on the internal interface would be spanned to all those member ports 1-5 just like regular trunk ports on the switches.
So once you created those VLAN 10 to 60 on internal (with Management IP), you can hook up each trunk port on those switches to any port in 1-5.

Toshi