Not to trivialize but it’s much the same as bartending. If you would serve them another drink, even if they have had a few drinks, then it is probably consensual, despite the involvement of alcohol by one or both parties.
But if she(or he) came up to the bar and you would suggest to them having a water or some food then probably out of the realm of legal consent.
Am I crazy to think of it that way? Been in a relationship for a long time so I’m probably a little out of touch. And I hated bartending.