Huge difference going to GP5000s. Huge being ~10% or 2mph at 20mph. What else can make that difference (besides rider position, lol).
I've been riding GP5000s on very fast club rides (25-30mph) on my gravel bike. Everyone else is on 25mm tires at ~100psi. Yet my power readings are 5-10% lower than most of of the other riders. With the crap asphalt we have here, the bigger tires are faster (our asphalt is worse than some of our gravel). I've oversized them a bit to 38mm - and everyone else assumes I'm working harder than them. They really look a LOT larger than 25mm tires, yet are fine on MUP, chloride covered dirt, and rough asphalt (I run around 40psi).
Unlike the above posts, I'd really recommend the 34mm Schwalbe Pro ONE TLE. Realistically is is only 1mm larger than the 32mm GP5000, but it seems to me to be a lot more robust.
I'm a little luke warm on the aero. It depends a lot on your apparent wind, but my long solo rides tend to be at speeds where aero doesn't make too much difference (unless it is a windy day of course).