Hello,
I have actually the exact same question than this user: https://forum.opnsense.org/index.php?topic=2252.0
Since it seems not to be in "System: Settings: Miscellaneous" anymore.
Has been moved ?
Thanks folks !
For next peoples who are wondering too this trick worked smoothly:
https://forum.opnsense.org/index.php?topic=3833.0
I don't know about HTTPS, but for HTTP it went immediately after a reboot.