The useful question is never “does this add value” — it is “how many buyers will this rule out?”
You will find articles claiming a given feature adds a precise percentage to a home's value. Those figures are not traceable to anything, and we do not publish them.
The honest version is about the size of the buyer pool. A feature that appeals to most buyers keeps your pool wide, so the home sells reasonably in any market. A feature that only suits a few narrows it, which usually shows up as a longer sale and more negotiation rather than as a lower asking price.
The pattern: buyers over-weight what is visible and cheap to change, and under-weight what is structural and permanent. The market, over time, does the opposite.
A garage, particularly attached. A functional, conventional layout. A legal suite where the community supports it. Green space or a protected outlook. A finished basement that was permitted. Off-street parking. And a location with a short commute to somewhere a lot of people work.
None of these are exciting. That is rather the point — broad appeal is what a resale is made of.