Does designing an ionic application give the ergonomics to modify all the components as much as possible so that it resembles what the ui/ux designer did on figma?
Not necessarily. You can customize quite a bit but not everything. Know though, you don’t need to use all the Ionic components, you can pick and choose.
I would just suggest using the main building blocks (i.e. routing, tabs, modals, maybe buttons) so you get the feel of a mobile app out-of-the-box and then create custom components to match your Figma design.