How set it up my new EPSON et-2850 connect my Imac

This printer supports AirPrint, which means vendor drivers are not usually needed. I’d usually avoid adding third-party printer drivers too, if AirPrint does what you need.

Connect the printer to your Wi-Fi network:

https://files.support.epson.com/docid/cpd6/cpd60021.pdf

Update the firmware from the printer control panel:

https://download4.epson.biz/sec_pubs/et-2850_series/useg/en/GUID-033AF2DE-E9D6-40C3-9150-F9E1612411D6.htm

Tell macOS about the printer:

Print wirelessly from your Mac to your printer - Apple Support

While an iPhone will find the printer automatically once AirPrint has been set up, optionally tell your iPhone (more) about managing the printer:

https://apps.apple.com/us/app/epson-smart-panel/id1477796092

Here’s the reference manual: https://files.support.epson.com/docid/cpd6/cpd60206.pdf

I'm not familiar with Epson printers but installation manuals and videos can be found on their website. You may have to select a different country for your own language for easier reading.

Epson ET-2850

jvanoestren wrote:

Why iMac is WiFi can’t printer is not working at all is not good

You will need to read the previously-linked Epson documentation.

You’ll also need to connect to a functioning Wi-Fi network.

If English is not your preferred language, please re-post your question in a language you are more comfortable with, and we’ll try to work with that.