Make Access fully MDI
Although the UI of MS Access has been modernised with Office Fluent Ribbon, Access is not fully MDI - all the displayed objects - forms, tables etc.. still display within the current window. How about keeping up with Word and Excel programs, have the option for each object to display in a separate Window?
Also, through custom VBAprogramming, you can open up multiple instances of a given Access form within a single running Access application.
Did you try Options | Current Database | Document Window Options: Overlapping Windows selection option?
Patrick Headley commented
Your request is already a reality. You can open multiple instances of MS Access and display different objects in each instance.