Much of it depends on the dealership you plan to get any work done. Some adhere to the Ford guidelines by the numbers and that is that. Others will overlook some things. Then there are things which you pay the dealer to do and the warranty stays in tact versus if you do the work. You install a tuner on the vehicle and most dealers will say no warranty. yet if they sell and install it that changes. Then 5 Star Tuning sells a warranty which kicks in should Ford deny a claim.
Should you start changing out lights and altering wiring without understanding how it affects some of the various computers which monitor the current, BMS, grounds, etc and it goes in for warranty,things could get interesting. While the Magnusson Moss Act provides some protection Ford is known to blame you first and deny until you prove otherwise.
Best thing you can do is ask what the servicing dealer will be tolerant of and hope it never breaks outside of that area since another dealer could feel otherwise. Yet you will findsome have all kinds of mods with a blown engine or trans who never experience an issue from a dealer. While others looked crossed and can't get a dealer to fix something pretty obvious.