Spoiledhappywife, how much money are you willing to spend? I've spent lots of time researching ways to lift the 2018 Expeditions. My wife and are planning to do a major house renovation next year or ours would be getting a custom set of King coilovers front and rear. Most of my information is off research with no real proof so I'd say I'm 99% sure its correct. The only difference between the 07-13 suspension and the 14-17s is the bottom mount of the front coil overs. And I have not been able to find any differences from the 14-17s to the 18s. I've looked for any information from ford press releases of whats been changed and I've even searched part numbers.
I'm not a fan of spacers because they lose suspension travel, and I don't trust them because my Expedition is no pavement princess, but if thats the route you're going, the 3/2 spacer sets that fit the previous models, still fit the 2018s.
I took a look at Rancho's leveling kit for the 07-13 Expeditions and found out extended and collapsed lengths of the shocks they offer. I found the Bilstein's below that have the correct lower mount for the 14-18 Expeditions and have a matched extended and collapsed lengths from the Rancho's. They are from a 2wd 2015+ F150 and they are adjustable so you can lift your Expedition without needing a spacer. I found a thread on this form from a member that put the 4wd F150 variants of the Bilstein 5100s on his Expedition, he said that they are 1" longer then the Expedition shocks at the 0" lift mark. These 2wd Bilsteins below are 1" shorter then the 4wd variant, so there should be no suspension travel loss.
https://www.4wheelparts.com/Suspens...h1OBQdzEAQYASABEgKZN_D_BwE#overview_Container
As for the rears, from the part numbers I could find, nothing has changed other then the coil spring capacity. The only quality rear shocks I can find are the Bilstein 4600 series that fit the 07-13s should still fit all the Expedtions up to 2018. But they wont provide any lift, so you still need a spacer if you want to lift.
So there you go. You have a cheap spacer option or a mid-level option. And if you got tons of money to burn, you can get a custom setup like I plan to eventually.
Any questions, or if I missed something, let me know.