A mobile device and WiFi is required to set up the Beam in the Sonos app. Read more here:

https://support.sonos.com/en-us/article/set-up-your-sonos-beam

Once the Beam is set up and connected to a TV, you can control the Beam’s volume using the TV remote with or without the Beam being connected to WiFi.

So the Sonos soundbar is wifi and cell phone dependable. Even the Sonos soundbar has been set initially, the user still cannot adjust the soundbar bass, dialogue etc without the wifi and cell phone. Is it correct?

What’s your native language? It might make things easier…

As @GuitarSuperstar said, once the Beam is set up, you should be able to use your TV remote to control the volume. It uses CEC via HDMI-ARC, if that is any help. An internet connection is required for initial setup. 

Once you remove the internet connection, you wouldn’t be able to adjust other settings, though, without a Local Area Network that the device running the controller and the Beam are both connected to. 

The Sonos soundbars are part of a range of multiroom wifi speakers an designed to take part in the multiroom network. This makes them more versatile, but also more expensive. While they can function without wifi for TV-sound (after being set up on wifi and with a cell phone or tablet), they are indeed dependent on wifi and cellphones to use other functions  normally doen while setting up a system, like tone adjustements.

If you do not want (or are able to) use a cell phone and wifi, maybe Sonos is not for you. For those users a (probably cheaper) soundbar would be better.

The Sonos soundbar is not compatible with  the Blutooth, right? What is the easiest method to make the Sonos soundbar to play the sound by a cellphone? 

If its an iPhone then you can use Airplay.

However, there are no Sonos devices that work as a microphone for a cellphone. 

@compiler It would be easier if you tell us what you want to achieve with the Beam.

If you have the phone, why the questions about setup and settings adjustments without a phone?