If you write direct speech within single quotes (common in novels) and you have auto-convert dumb quotes to smart quotes turned on then, of course, apostrophes are recorded as the curly smart close-quote character as you type. Nothing wrong with that, I suppose, but it can sometimes be confusing when you have apostrophes inside direct speech. And since the distinct dumb single-quote is now an unused character, why not employ it as an apostrophe?
You can’t do that as you type (coz auto-convert takes place), but, working on the finished document, you can use the Find and Replace box to replace all curly close-quote apostrophes with dumb apostrophes while leaving open and close quotes as they are if you set the RegEx option under Find Options.
The required Find string is
This says find a string comprising the sequence: letter, curly close-quote, any character (except a line-break).
And the required Replace string is
This says replace the middle character of the three-character found string by a dumb apostrophe.
It’s not going to improve the quality of your writing, but it might offer a tiny bit of optional smartening up (plus the satisfaction of using RegEx). It works with my writing style, but you use this at your own risk (see CAUTION below).
This search for apostrophes assumes that you always keep your punctuation inside your quote marks (as recommended in style guides) like ‘I would,’ said James, and never ‘I would’, said James or ‘I would’ said James (those last two would detect the close-quote as an apostrophe). Also that you don’t use other exotic punctuation. Someone cleverer than me at RegEx could resolve these risks.