Actually, if it were legal, the deaths would be far, far, less because it would be manufactured to standards and not sold on the black market, put into other narcotics as a poison. Most fentanyl deaths aren't overdoses at all, they're poisonings where people didn't know they were taking fentanyl.
More people die because of sanctimonious authoritarians try to force people to live by the beliefs of the sanctimonious rather than choosing for themselves.
And, no, abortionists, this is not an argument for you to choose to kill babies. Your right to choose for yourself doesn't include choosing death for someone else.