How to optimize search by tags?

I will be selling shirts on my site, some designs may feature the same element, for an example let’s say “Apple”. Each product page that has an “Apple” in the design I would put the tag ‘Apple’ on the page. So it makes sense that if someone uses the main search for the term Apple, it would show all products with that tag.

It is not working like that now. How does the search function work? Is it possible to search by Tags?

Thank you.