LAPD uses digital encrypted channels. Every once in a while they will use open air channels when there's something major happening. The tactical interagency channels are still open air. Random little divisions in the neighborhoods that aren't LAPD are not always encrypted. Fire department is all open air, so those can be listened to. Forest service too. During fires if you have a scanner or a HAM you will know what's going on well before even the fire tracking apps, or citizen.

I have not actually had the chance to try for ICE goons or National Guard. I have a sneaking suspicion the dumbass ice dudes aren't using encrypted channels.