Yeah, I put a moderate leveling kit on a 2020 F150, along with a grill guard and winch and barely saw any MPG change. I've heard they can drop fuel economy, but I didn't see it.
I can't give you clean data. I put a 2" leveling kit and 35's on my 2020 f150. I think it dropped my mpg by 1 mpg or so, but it's hard to say. Probably mostly the bigger tires. I honestly don't really calculate mpg in my truck.
Put a leveling kit on a 2013 w/ Ecoboost. Also put on 10” wide rims with spacers so my tires extend outside the well a touch. That combo dropped 1.5-2 MPG but looks and rides much better. Setting it up for my soon to be 15 yo.