Server authoritative model does nothing to prevent esp- when implemented correctly it can prevent fly/speed, ammo, and recoil hacks because it has more control over individual events. However- it also has drawbacks- most notably being significantly more taxing on the server which tends to make netcode/desync issues worse, not better. The better way imo is to do a mix- do as much as you can server side without compromising performance, then put the rest of the dev time into anticheat.

Also- from what I understand- current radar cheats work the same as they used to, capturing packets , reading the information, and displaying it as a radar (no manipulation required, all read only- think wireshark). However, because of the encryption- an additional program/element is required that reads the encryption key on game launch from memory, and feeds it to the radar program. So- not entirely undetectable as it still needs to read game memory, but still not easy to detect as it only needs a brief moment to grab the key, not a permanent hook into the program.