Here is some in information on the horn replacement.
In the end I took off the hood latch and was able to reach in that way. If you have big arms you will need a plan B. Take off the plastic cover held in by about 12-15 plastic clips. Then take all the bolts and the 2 plastic clips from the metal cover under the plastic one. Just so you can move it forward about a 1/4 inch, maybe, to get a little more access to the the mount bolt. When installing the bolt back in hold it with a pointy nose pliers and start it with a 10mm open end.
My 2019 Limited horn was so embarrassing. The replacement was on 2017-2018 expeditions and the current F150. Maybe they had a supply problem. Mine only had one horn instead of the dual. Now it's a real horn sound.