How to arrange apps in iOS 12

If the apps don't jiggle on devices with 3D Touch, that is usually an indication that you are pressing too hard. Trying touching and holding lightly.

The method should be the same. If you upgraded to an Xs from a non 3D touch enabled iPhone, it is a bit different.

Instead of pressing down and holding it, just lightly tap and hold on an icon until they all start shaking. The hold is very light so you don't engage 3D touch.

This may help, How to move apps and create folders on your iPhone, iPad, or iPod touch - Apple Support, but it is the same as it always was, but as Phil0124 and FoxFifth stated, it takes a lighter touch.