I am working on something similar to delivery app. When delivery guy accepts the order , how to change screen of customer dynamically?
I am working in React Native frontend and Express JS backend. I need some references and code as well.

How would we suggest anything if we know nothing about the architecture you're using? There are dozens of ways of "changing a screen dynamically". If you mean in real time, one option is to use Web Sockets.
But again, at least point to a repo.

Also... as much as there are people wanting to help, this ain't no Stack Overflow. Keep your coding questions at the minimum, bring the rants up.

Welcome to stack overflow.

Me dumb-dumb, me needs the codes for help

on express, no, no. js too skinny, too skinny for that, OP.
me thinks golang, java or erlang be best, OP.
me picks java, ditch React as bonus, yes, yes.
OP gets app done faster, yeah, yeah, many sugars, yes, yes