What version of Fusion?
On Fusion 12 Player, I just created a VM with an OS type of “Windows 10 and later x64”. During the VM creation process, a dialog appreared that offered to use BIOS or UEFI, and the UEFI option had a checkbox for Secure Boot. That process placed the following 2 lines in my .vmx file:
firmware = efi
uefi.secureBoot.enabled = “TRUE”
So at worst if these 2 entries are in the .vmx file Secure Boot should be enabled.
I could have sworn that I saw a selection box for this in prior Fusion versions for Secure Boot by going to Settings -> Advanced for the VM. But I’m running Fusion 12 Player, not Pro and that selection does not appear in Settings. I can’t tell if the ability to enable Secure Boot in the Settings is present in Pro. .