Since you want the ability to play Dolby Atmos audio and your projector probably doesn’t support Dolby Atmos, I recommend getting the HDFury Arcana eARC adapter along with an HDMI switch. The Arcana will allow the PS5, Apple TV, and PC to bypass your projector’s limitations and send audio directly to the Beam.

Before you connect the Arcana, be sure to set up the Beam with a TV with HDMI ARC first since your projector does not have HDMI ARC. If you have already set up the Beam on a TV, you can skip this step.

HDFury Arcana: https://hdfury.com/product/4k-arcana-18gbps/

Here is an HDMI switch that works well with the Arcana: https://www.amazon.com/dp/B07CF793HQ/

Ok so i connect PC ps5 apple tv to the HDMI switch then i connect HDMI switch to Arcana and Arcana to Beam and projector right ?

It will look like this (ignore the TV/monitor):

Ok perfect !

 And what do you mean by setup beam with HDMI arc, i need to set up the beam on « arc mode » ?

problem is i don’t have any TV at home ahah

From the Arcana manual:

In order to get audio from any sources at Arcana input, users of brand new/never used Sonos Beam must go through the app setup process while connected to a CEC-capable display. If you never when through the Sonos app setup process with your Sonos Beam soundbar yet, please connect it to any HDMI display that offers CEC support and complete the Sonos app setup process. Once done, you can connect it back in your setup with a non-CEC capable display, monitor or TV and you will be able to get full audio from any source to Sonos Beam as expected. This Sonos restriction requires such initial setup first with CEC-capable display. If your Sonos Beam has been setup before, then there is no need to set it up again after the Arcana is connected and you can just proceed normally.

If you don’t have a TV, take your Beam to a friend or family member’s home, connect it to their CEC-enabled TV, and run TV Setup for the Beam.

This is where we start the tv setup right ?

tv need to have a Earc hdmi no ? or i can do it on any tv 

No, that is just select the TV as a source after it’s been setup.

The setup to connect a TV should normally occur when you do the initial setup of the Beam (connecting to internet, etc).  If you’ve already done that and skipped TV setup, I believe you can do it later under the settings.

https://support.sonos.com/s/article/2659?language=en_US