I want to use ESP-NOW with esp32 and esp8266. The esp32 will mostly send data to esp8266.I was not able to find any good tutorial on YouTube to achieve this. The only videos I found was for either communicating with esp32 to esp32 or esp8266 to esp8266. Is it possible to do this if yes how.
In general, ESP-NOW uses the WIFI radio in an ESP processor as a physical layer. But uses it's own protocol which likely looks like garbage to a normal WIFI equipment. So, it's like being in a meeting room with a bunch of people only knowing German and occasionally someone pipes up taking French. As no one understands the French speaker, the French speaker is ignored.
Other things you need to know. ESP-NOW is more like UDP. There is not a higher layer looking out for you like in TCP. Any number of reasons can cause your ESP-NOW "blurp" from being received. For this reason ESP-NOW is better suited for periodically repeating information. Like reporting the temperature. Or for situations where the user can provide immediate feed back of success. Such as a remote control.
The esp32 will mostly send data to esp8266
This infers reversing the direction of data flow over the ESP processor's WIFI radios. While this may be possible it may not be a trivial task.
Is it possible to do this (communicate between an esp32 and esp8266) if yes how.
This shouldn't be problem. This link provided by Majenko appears to be a good place to start. Espressif them selves maintains this ESP-NOW web site. Likely, after programming the ESP8266 and ESP32 using the correct libraries, they will be able to send data over an ESP-NOW link.