There are some things that maybe you would like to research but are a super private matter. Let’s say you want to research an STD you think you might have. Or let’s say your pregnant and don’t want others to know yet. Trust in a company means you trust to not share this information. Not used as possible ads for creams and baby formula. Especially if you are unsure of either and don’t want somebody else that may use the same computer to know.
For questions like this, use Tor browser. Tor clients route your connection through 3 hosts (a guard node, a relay node, and an exit node), and the last two will not know who or where you are.
Tor browser also has an incognito/private mode, at least on my Lineage Android and Ubuntu desktop. Set a desktop shortcut to incognito, and never use the mode that retains cookies.
Google does not like to talk to exit nodes, and will throw lots of captchas. If you want to search with Google on Tor, use startpage.com instead.
DDG, Ecosia, and others are really just Bing in disguise.
I'm not sure how friendly some of the other boutique search engines are to Tor. Malicious actors can use exit nodes to launch attacks, although I think safeguards have improved over the years.
I wrote an article on Tor for Linux and Android a few years back, and it has some more detail that might be useful. Let me know if you want the url.