When running in windowed mode, the title screen and the fmv's are stuck on a resolution of 640 x 480. Meanwhile the game is running on your chosen resolution (for example 1280 x 960). Basically the transition looks inconsistent.

To fix this annoyance you can download Windowed Borderless Gaming.

https://westechsolutions.net/sites/WindowedBorderlessGaming/

Once downloaded, run WindowedBorderlessGaming.exe and Launch Tomb Raider (1996). Press F3 to add the window.

In the system tray (bottom right), right click Windowed Borderless Gaming and go to Settings -> Game settings. Add the resolution you want and click apply.

Now go to Tomb Raider Folder / Patches and open dosbox.ini/tombati.ini. Change to resolution_override = true and enter your desired resolution.

Go back to the main folder and open glgrage.ini. Change to fullscreen_mode = 0 (1 also works).