Hi
On the Photo watch face, it is possible to customise the position of the time and accompanying complications. It is also possible to customise what is shown in the two complications (which show information alongside the time - such as, for example, Date, Calendar, etc).
However, it is not possible to customise the colour of the text.
If you would like to submit a feature request to Apple, then you can do so here:
Feedback - Apple Watch - Apple
More information:
Customize your watch face
Change your watch face - Apple Support
Faces and features