Here are three examples from negatives which were slightly overexposed, which I believe improved the intensity of hues. Or at least gave the colours from film which would otherwise yield flat colours with normal exposure. These are print scans. The change in saturation or intensity is really hard to show using these alone, without comparison, and many of the tones largely lost.

This one is from about 10 years ago. Shot on Imation (Ferrania) 100 film. This film, normally exposed, gives a pastel palette:



The following are from last year. Shot on Luckycolor 200 film, which again, isn't known for punchy colours. The film was exposed at EI 100 instead.





Articles and reviews about colour film negatives published in 1990s photo/trade magazines will likely mention something about the slight overexposure = colour punch routines. Check the American "Popular Photography" or "Modern Photography" (defunct by the early 1990s) features on colour films from this era.

Most amateur colour film negatives also have official ISO ratings which are lower than their real speeds. Many ISO 100 colour negative emulsions often had real EIs of 160 or even 200. That assured some overexposure- giving both the extra colour punch and an exposure "safety" factor.