Ecosia[0] does this by using a hash sign at the end of the string instead, like "query #g" to google "query". I prefer that to DDG's bangs, but ecosia only has a couple of available options[1].

e: Apparently DDG can do this after all, so ecosia is actually less flexible since the search tag has to come at the end!

[0] ecosia.org

[1] https://ecosia.zendesk.com/hc/en-us/articles/201657321-What-...