Yes they will thats true. That doesnt really matter for a lot of stuff. For example you use it to update everyone on what's going around in different areas. The police already know this information. Them hearing it doesnt change anything.

Phones are a liability in ways radios are not. Unless your using a phone that is used only for this protest and then discarded the IMEI can be tracked and it is forever linked to that protest. If its ever used in a way that identifies it as yours afterwards then you are now also linked to that protest. Also if your phone is taken it could potentially be a treasure trove of information on you and anyone you know. Which they can use to bring criminal charges in many cases over pointless bs. A radio doesnt have internal storage of anything sensetive.

Phones can also be highjacked by stingray devices remotely and all traffic monitored. e2ee helps but they can still track your device, sim card, etc.

As for how to communicate without the police knowing what your saying in a radio. Designate meeting areas, and landmarks prior to the protest with code names.

Mcdonalds can be Katy Perrys House for example. On the radio say "Guys lets meet up at Katy Perrys house." The police have no idea what that means.

There is no need for fancy encrypted radio. Coded language like this works just fine, and cant be deciphered easily.

Heres an example. You are out at a protest when you see a big line of riot troops coming toward you. You get out your radio and say "Cops incoming lets all head back to the eggplant factory."

Someone gets hurt and needs help. "I sprained my ankle im 500 feet south of Hillarys emails can someone cone get me?"

cops will hear that, but its gonna mean absolutely nothing to them. All they know is your leaving, or someone got hurt. In a crowd of thousands thats close to useless.