Male configured 'outlet'
Such connectors are readily available. Search for "generator power inlet". Here's just one example, from Northern Tool:



Of course, when you install one of these, it MUST be wired so that it can only connect to loads, not to other power sources! That's what a whole-system or per-circuit transfer switch is for. Here's a small one that happens to have the connector built into it, from Reliance, via Grainger: