A fascinating and academic deep-dive into how studies of extant organisms and trends in living animal groups could be used to infer colouration and patterning in extinct creatures (specifically here looking at theropods).

On the colour and patterning of extant top-level predators:

Across vertebrate groups, and across habitat types, our biggest modern predators are pretty consistently (maybe entirely consistently) primarily coloured for concealment: that is, they have camouflaging colours and patterns which hide their presence from their prey.

On a possible pattern (not precise correlation) between extravagant ornamentation and colour/patterning:

Faces are often sites for signalling patterns and colours in modern species (e.g. Caro et al. 2017) and a reduction in bony facial ornament could indicate a lessened emphasis on this behaviour, possibly including muted facial colouration.

On other factors that impact colour selection and some of the surprising pros/cons:

Darker pigments, for instance, can protect skin from harmful UV rays and may have antibacterial properties but, conversely, also absorb more solar heat and increase an animal’s thermal load

On how it is likely that dinosaurs would have significantly changed colours across their life:

We should not imagine that juvenile theropods transitioned to their adult colours straight away, however. It took decades to grow gigantic theropodan predators and, in all probability, the route to adulthood was via several different ecological niches (e.g. Holtz 2021), each of which may have had different adaptive pressures on colouration.