Actually ALL law enforcement personal be they municipal,county, state or even conservation officers are REQUIRED to have their CERTIFIED CREDENTIALS with them at all times while on duty. It is not the uniform or badge which really identifies them to be police officers it is their CREDENTIALS.Wonder what cops would say if a citizen said "I'll gladly comply as long as you show ID proving you're really a cop first".
Yes, it is your right to request to see these & they must show them if requested. Human nature being what it is....they will be taken aback if you do ask.
I know this to be a fact because of my experience in law enforcement & taking the mandatory instruction conducted by the Pennsylvania State Police regarding essential requirements to be able to legally arrest someone while serving in the capacity of a police officer
Without proper CREDENTIALS you probably cannot even direct traffic & be covered by state provided liability insurance ....for sure you may not make an arrest or perform in the capacity of a police officer without CREDENTIALS.
Know your rights, but be very careful of when & how you voice them.