Highlight Color (The highlight itself, NOT the text)

My vision is deteriorating, and I am having trouble seeing the text that I have selected.

It would help considerably if I could see the box color that shows what is being selected more clearly.

I can find no setting, nor help from Internet or Apple Help.

My Mac shows a nice, bright blue box, but my iPad shows an almost (to me anyway) invisible yellow / orange.

Any help would be appreciated.