The three screenshots show replaced assets, replaced font and an altered meta file to change the police response in Valentine to Saint Denis police. It also includes full UI support akin to the GTA V version.
In its current state for RDR 2 it will allow you to replace any file in the game, whether they are streaming files such as models or data files, font files etc. The general idea of Lenny's Mod Loader is to provide an easy way to modify the game.