Hi.
The issue is that ALL of your textures are 2k resolution. IOS has it’s own thing and some limitations, and the issue you are describing usually comes from the large textures. It’s really not easy to define how many textures you can have, and how large they should be to avoid this issue. I usually keep it to this rule though → “Limit your textures for IOS to MAX 1k resolution”. If you have a lot of textures, even this might be reduced in some places.
Basically, it’s not that you cannot have 2k in the scene. If it is really important keep it, but reduce other textures. If it is not really important in the scene, reduce it to 512 or even less. Try to keep balance with this and test it out.
The example model that you shared that CAN run on IOS, if you check, has only 1k textures.