Those aren't meant to look like fake air intakes. They're fake fog light deletes. The Mach 1 is supposed to be the heir apparent to the late GT350 and before that the 2012-13 Boss 302. The latter of which had similar grill fog light deletes(which could technically be made functional with the addition of GT fog lights). In this case there was never fog lights available in the grill for the Mach 1 or even for the newer GT for that matter.
There is no dual air intake for the car and there are no fog lights either that I know of.
Being a that very few of these are out there compared to the GT and Ecoboost there will be precious little available in the aftermarket specifically made for the Mach 1, if you can find anything at all even, other than any optional equipment that didn't come on the car from Ford that you might be able to add.
There has been a clamoring from the small Mach 1 community since it was released in 2021 for some company out there to make a fog light kit but I haven't seen any advertised. It's a numbers game and there probably just isn't enough willing Mach 1 car owners to make it worth making. Therefore, you would have to do your own custom work. Take note that since it's brand new and an expensive limited edition any noticeable modifications made from stock will tend to devalue the car.
The 2021 Ford Mustang Mach 1 Grille Has Empty Spots for Fog Lights of Your Choice (thedrive.com)