How to communicate 2 ESP8266s with each other without using a router?

Welcome,

I want to make a circuit that will measure the temperature and send it wirelessly to a receiver with an LCD display. I have chosen the ESP8266 WiFi chips to implement the transmission, I know how to do it using a router and 2 modules. But the task got a bit complicated for me, because this device has to be portable, so the chips have to communicate with each other directly. Can the ESP create its own WiFi network to make this kind of data exchange possible. Maybe the idea is to use mixed mode, but how to implement this. Please help if this is at all doable without using a router.

Google -> "ESP8266 ad-hoc" or "ESP8266 mesh".

You can set one ESP to AP mode and the other to STA mode.

If you want to do it under Arduino this will help you:
https://www.geekstips.com/two-esp8266-communication-talk-each-other/