I use also Brave and Presearch. But, If you still want to use your preferred search engine by default and with presearch (Qwant, duckduckgo, etc...) on a new opened tab, you just have to configure Brave with presearch engine and set the url as : https://www.presearch.org/extsearch?term=%s

With this the presearch url will be called and presearch will route to your search with your search engine by default you set on presearch.org