Earlier quoted context omitted.
Airplane mode has wifi enabled by default nowadays
Just go to settings and disable. I do that every night. I don’t want or need to be available.
You should leave your phone on when you are asleep with full trust and confidence that you won't be disturbed except in a real emergency. The do-not-disturb mode is for Friday nights where they is no way for someone to know if you are the theater or just chilling at home - the latter is an acceptable time to call.