If everything is set up correctly with the DVD player set to 16:9 or 'widescreen' you will get widescreen movies as is. But if the aspect ratio of the film is greater than 16:9 (1.78:1) you will still get small black bars across the top and bottom.
Even if the DVD player is set to 16:9, playing a 4:3 or 'fullscreen' movie will show black bars on the left and right. The only way to get it to fill the screen is to use a stretch or zoom mode in the TV.