Multiselect in separate page

I have a big form with like 16 inputs, going from basic inputs, selects and multiselect. Now I want to reduce the cluttering for the user by moving the more advanced inputs such as multiselects to another page or fullscreen modal, so like that if the user wants to use any of it he will be having it cleanly in another screen.

I've seen many website do it and I don't know it's really the right thing to do or just use another alternative methode such as collapsibles. Should I separate it or keep it in the same page ?