You can use bangs in Brave Search.
!d → DuckDuckGo
!g → Google
Note that using bangs is simply a faster way to search something using a different search engine, bangs don’t protect your privacy from the different search engine. Said in other words, using !g something in Brave Search will redirect the search query to Google, and from then on your privacy protection depends on Google rather than Brave Search.
@Mattches do I remember correctly that a documentation is in the works?