There are what are called Standard Places, which in general are anything down to level 1 geographies, which means national borders and first level political divisions (provinces, states, departments or whatever they are called), as well as continent level definitions. These are only editable by iNat employees.
Anything finer in scope than this (cities, parks etc) fall into ‘Community Curated Places’. And these can be created and edited by all users, who have created a minimum number of observations. There are some restrictions to those editing abilities : kml must be less than 1mb in size (5mb for site curators), and must be less than about 500,000 square kilometers (or roughly the size of Texas). Most existing community curated places can be edited by all users, but some for some reason are locked.
If you have a precise map for a location that defines for example a city, in particular if there is already an attempt to create it that you can not edit, the best approach may be to reach out directly to help@inaturalist.org and send them the kml file and ask them to integrate it. Anything to avoid duplication is a good approach.