You'll need to use a Content Delivery Network (CDN) or make your own. It could be as simple as downloading files over http or integrating into something like Azure.
Unfortunately you're limited in how much data can be stored locally. I don't know the best workarounds for this but you'd need to figure out a plan before you commit to any system.
There's also the matter of dynamically loading sprites/etc., which Construct does well but you'll need to do a fair bit of setup to make it work like you want. For example if you're adding new objects with their own collision polygons and instance variables.
For my own projects, I tend to only use a CDN to pull through data (json and html files) and a handful of images for special events in the game. All other objects are loaded into the project, even if they're not always used.