Magento 2 – modify search

I’m developing a Magento 2.3 shop.

I want to modify the search terms before sending them to the searchengine (database). At the moment I’m stuck where to hook into the code. Can anyone give me a hint, which class / function handles the search term and sends it to the database?

Normally I’m fine with the standard mysql search engine, but I want to replace / delete / modify certain words from the search term.

Joerg