I see what you mean, not all materials in my project use multiple greyscale textures that I could combine. HOWEVER, i found a plugin similar to the one you mentioned and did pack a decent amount of 4K textures. I also removed a few tree/foliage assets I was using only once or twice. I am exporting to iOS right now with my fingers crossed it works!
With the future in mind, i will not implement multiple nature scene marketplace packs into a iOS/ android project.
EDIT: Packaging failed, still over the 2 gig limit. The new village houses I added all use 4k textures and look like ■■■■ when I reduce them to 2K. The village pack alone has 2.05 gig of cooked content ): I will have to rethink things heavily unless there is a way to avoid this file size capacity. Apple for sure accepts apps up to 4 gigs so I’m not sure why Unreal doesn’t increase this cap.