Trying to hookup a 30A 220v espresso machine in kichen. Can I use a 30A 250v dryer outlet?

Thanks adam

In the US residenitally it is all basically 240V. Some major city apartments might have 208V, but that's a different situation.

Your dryer circuit is 120/240V, not just 240V. If it is a 3-prong receptacle then you have two hots and a neutral. It's not proper, but you can use it for your espresso machine.

The opposite would not be true. You could not use a ground as a neutral.