Greetings to all! I wanted to clarify where and how to add add-ons to the category tags, not so much in SEO promotion, but in ad search. That is, you need to find a car, according to these words it should already be in the search, <ca, ma, bmw > b and so on. How can this be implemented?

Sorry did not get your point.

For example, there is a word that, when we write in the search bar, and if there are ads with such a word, the search will find it, but if there is the slightest deviation from this word, the ad will not appear on the search page.
For example, I have an ad that contains the word cow, but if I write bull, then my ads will not appear on the search page.
How to combine certain words, and link them together.

Mysql might match it when searching in boolean mode... alternative is just to write keywords at bottom of description.
That's best way.