Is there any way to increase the detail of the in-game character models in DOTA 2?
If your system can handle it, the following console command...
... will increase the detail level of the in-game models to match that of the portraits. The actual difference varies from one hero to another. You might get a sharp drop in FPS in games with lots and lots of models though (like Phantom Lancer or Naga Siren illusions, Meepos, etc) so you might want to test that out in a bot game or something. The same command with