VLC Python Instance does not stretch the mp4 files in 16:9 ratio

Question

import vlc        
self.instance = vlc.Instance("--no-xlib", "--fullscreen", "--video-on-top", "--zoom=2")
self.player = self.instance.media_player_new()
self.event_manager = self.player.event_manager()
self.event_manager.event_attach(vlc.EventType.MediaPlayerEndReached, self.end_reached_callback)

self.player.video_set_aspect_ratio("16:9")

self.player.set_fullscreen(True)  # Abra o VLC em tela cheia

All files are being opened in a full screen mode but not with the 16:9 aspect ratio. If I open the VLC player itself and go to Video tab and Prorpotion It can be manually adjusted. In my script it does not occur.