I have no cash right now to pay the fed/state taxes I owe. Is there any way to get an extension on the cash I owe? Or the only extensions available are filing extensions?

I'm just very unclear, and I don't find the existing turbotax answers clear at all.  The form 4868 seems like only a "filing" extension, and I don't really see how that's beneficial really, if you have your full tax liability calculated.  But I have negative cash right now, literally, and I can't imagine there is no way whatsoever to get a payment extension....?