We don't use front license plates here and I cannot find anyone that makes an insert to fill in the hole in the bumper for my truck.
It leaves a huge hole to swallow rocks and debris into the radiator.
I had one on my 2013 and it worked great.

 

Have not had any issues with my truck without the front plate. If you want to keep rocks out, use a piece of 1/2” hardware cloth , paint it black and cut to fit.

 

I have 2021 Lariat with 501a package and the bumper is not the same as yours. Mine has a solid piece of black plastic with 4 slots for a license plate bracket instead of the three spaces like yours has.

 

Turbos have that open for cooling.

5.0 has a bumper trim piece there.

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I have a 5.0 This is a 502A Sport

 

13th gen with a block heater, had the egoboost lower grille. Likely the 14th gen does as well?

 

I had the exact opposite issue: I live in a 2 plate state and the dealer put a license plate bracket directly over that hole, covering ~60% of my intercooler. I ultimately just drilled through the thin steel in the bumper between the radiator grille and the interocooler, and I'll replace the whole bumper soon with a "ugly black steel" aggressive driver deterrent bumper. I could not understand how "obstruct a cooling intake" was the factory solution to regulatory compliance, yet here we are.

 

With block heater maybe?
Otherwise no idea why you're isn't closed as my exact same build is. I'd order the OEM Part like on my truck if I was you.

 

200,000 miles on two F150's never. ever had any issue like that

 

my 2011 Ecoboost had the factory plate mount just to the driver's side of that opening.... I think they moved it back to the middle because of the front radar/sensor