As I understand, a relatively outdated phone (Android 5, not updated for a few years) could be easily compromised by using security exploits through Wi-Fi, mobile data, NFC or Bluetooth.

I'm about to participate to an event where other people might try to hack into my phone (I suppose there is a similar issue when going to the conferences such as DEF CON). Given that NFC and Bluetooth are already turned off, is there any chance for another person to hack into my phone if I keep Wi-Fi and mobile data turned off as well?

Naturally, physical stealing of the phone is out of question, but the intruder can get within centimeters to the phone in a crowd.