Non-breaking Space

In your Pages document and with the insertion beam located where you want the desired space, press ctrl+cmd+spacebar to open the Character Viewer (Emoji & Symbols panel). In its search field, enter the word space. The blank locations actually contain various space characters such as the four-per-em space that is slightly narrower than the non-breaking space.

Double-click the space to insert it at your insertion beam location.

None that I've discovered.

You might try different fonts. The short examples below are in 11pt Helvetica Neue and Arial.

Setting text alignment to "justify text" may hide the difference, but will results in words being shifted in order to fill each line, creating even more irregular spaces.

Regards,

Barry

Then, see if the Narrow No-Break Space can get the job done.

DaveHagel wrote:

But that produces a much wider space than normal.

What font is that? My Pages default doesn't do that (Helvetica Neue).

Perhaps your font doesn't have that character and is taking it from another one?

DaveHagel wrote:

I am using Hoefler Text, which I really like, for my book. But its nonbreaking space is much too wide.

Indeed! Seems like a defect in the font provided with MacOS. I wonder if there is another with the correct (equal) width.

Discussed here too:

https://graphicdesign.stackexchange.com/questions/147243/hoefler-text-non-breaking-space-is-too-wide