Accessibility options for iPhone 17 Pro Max (for low vision)

I just bought my 90 year old father a new iPhone 17 Pro Max and now he cannot see his "Contacts" well. We changed the contrast and font size for his low vision but the contrast is lavender with white writing. Can hardly read it!! It appears we have to change EACH contact display to make it legible which is impossible because he has over 1000. How can we change the contrast throughout his phone - at least the native Apple apps? A chat gpt and then a google search make it look like others are frustrated that the Accessibility functions don't seem to apply to Contacts. Frustrating. Please help or @Apple, can you make this one of the updates?