If 2/3rds of Congress (in both houses - which is 67 in the Senate, and 290ish in the House) propose a new Amendment, that proposed Amendment can be ratified in one of two ways. First, 3/4ths of the respective State Legislatures may vote for adoption - how that process works, is dependent on the rules in each respective State Legislature. I think most are simple majority, but I'm not positive.
Second, a ratifying convention may be called. This has only been done once, for the 21st Amendment which repealed the 18th Amendment (prohibition). The rest of the Amendments were passed using 3/4ths of the State Legislatures.
"I wasn’t completely off, just missing a few steps. The states can call a Constitutional Convention on their own, but if Congress drafts legislation intended to amend the Constitution, the States have to call a Convention."
Not "have to" - may call a ratification convention. Or, they can simply vote to ratify it as individual legislatures, if they can get 3/4ths of themselves to vote as such.
Lastly, the other way to do this is for the states - 3/4ths of the states - to call for a Constitutional Convention. This, of course, has never been done except for the first Constitutional Convention.
Excellent! Thank you for the clarification, ODH. It’s been a while.