We've gone to great lengths in order to ensure that Odin can be dropped into any existing project. Odin will not apply editors for types that already have a custom editor. All existing property drawers will also continue to work and will be drawn with Odin without any problems.
You also have full control over which types Odin should draw via the Editor Types window found in "Tools > Odin Inspector > Preferences > Editor Types". From there you can enable and disable Odin for particular types, or get an overview over you existing editors.