I have been working in ARKit for the last few months. I will get the dae file. Import it into scnassets and convert it into scn file. Each file will be of each size. Say like 20 MB or 2 GB...
My doubt is the what is the maximum size of the dea file I can use in my app. Is there any limitation, or I can use any size.
The model that ARKit will display, must be first loaded to memory so if the size of the model is too big you will get memory warning alert and your app will crash. There you have it, memory is your limitation. Here is some old post about how much memory can iOS app use. Test it and you will see.
For best performance and great AR experience you should optimise your model the best you can. Here are some guidelines on how to optimise models for AR, I hope it helps: 3D Model Guidelines