Pages-Font Colour Change throughout except for undo button

The only decoration color control you have over Pages is via the Accent color from the System Settings : Appearance panel. I chose Blue because the yellow color is abhorrent. That also controls the insertion cursor color. The selection color is controlled by the Highlight color setting on that same panel.

That's on the Mac. On an iPad, or iPhone, your only control over the Pages appearance is to choose light or dark appearance mode. This will not alter the yellow control decoration or insertion cursor color.

Accent Color is found with Ventura and Sonoma on the System Settings : Appearance panel. In Mojave through Monterey — on System Preferences : General panel. These are not Pages v13.2 controls, and there is no iOS/iPadOS counterpart to these Mac-only controls in the first sentence.

Pages v13.2 is currently the last released version for macOS Ventura, Sonoma, and iOS/iPadOS 16 or later.

Although one can change the color accents in Pages v13.2 controls on macOS as I have explained above, there are no comparable controls on iOS/iPadOS to do the same, and Pages v13.2 on those operating systems will retain its unpleasant controls coloration.

Text in Pages v13.2 for iOS/iPadOS remains black for me on iPadOS 16.7.5 or iOS 17.3.1.