In Pennsylvania, it is illegal for an adult (someone 18 or older) to have sex with a minor (someone younger than 16), even if the sex is consensual. Those who break the law have committed statutory rape.

Can a 16 year old date a 30 year old in PA?

People ages 16 and older can legally consent to sexual activity with anyone they choose, as long as the other person does not have authority over them as defined in Pennsylvanias institutional sexual assault statute.

Can a 20 year old date a 17 year old in PA?

No law against dating. If consensual sex happens, the only potential crime that could be charged would be Corruption of Minors.