“They do. Routinely. Lots of them. FedGov even enforces the terms of treaties that were not ratified. “
Yes there are many unconstitutional things out there, but Constitutionally speaking a treaty can’t trump the constitution. That would bypass the amendment process. Liberals like to argue that since a treaty becomes law of the land it can trump the constitution but that’s wrong. It’s much the same argument that the constitution is a “living document” that is malleable to change with the time. It’s just an argument to try to end run the amendment process.
That was clearly the original intent. The Federalists were having enough trouble selling the thing as it was. Henry saw through it. Few others did.