Welcome to Android Central! Assuming you mean this phone (https://www.blissphone.com/), it doesn't look like that's a fully functional Android phone, but rather a featurephone. Can you show us any information that confirms it's an Android device?
I would guess that the phone is actually on Android Go, which is a pared-down version of Android for low-spec budget devices. Dev Options should still be available on Android Go, but it's also very possible that Bliss made some significant tweaks to the OS to block Dev Options, as Golfdriver97 mentioned.