Thanks, and sorry for sounding argumentative, I really wasn't trying to be (sorry, Meg). I am grateful to both of you for helping me understand my options. This kind of discussion does often lead to discovering features that I have overlooked. OK, I will provide a little more detail, but at this point I think I do understand the available facilities.
I primarily use this particular iPad Pro for displaying sheet music and running music apps. I do this on the bandstand and in my studio when practicing. The control center is very helpful because it lets me control audio playback while viewing sheet music or running other related apps. In other words, flipping to the source app would defeat the real advantage of having the control center.
So here's a use case. I'm working through an audio playlist of 20 songs. As each song starts, I flip to the associated page of sheet music and play along. The control center lets me do this quickly enough that I don't have to stop playback. However, if I can't read the title, then I must pause playback and either zoom in on the control center (now that you've shown me how to do that) or flip to the playback app to view the track information. This is not crippling; but if only the white-on-gray text in the control center were just a little more visible it wouldn't be necessary. Note that the black text is perfectly readable, it's just the white part. This problem is worse if the ambient light is very bright, and of course on the iPad Pro, the text in question is quite small.
I'm sorry for sounding a little frustrated, but my first assumption was "there must be a way to adjust the color scheme or the choice of fields displayed, but I can't find it." (There are many tweakable features, after all.) Having designed software products for much of my career, this one bit of low-contrast text stood out to me as something likely to raise a red flag during usage testing; so I was expecting to hear a chorus of "Yes, we agree." However, since you two apparently don't perceive this text as hard to read, perhaps it really is a question of old eyes.
Again, thanks for the input, and sorry for letting my frustration show.