Which specific Sonos speaker do you have?

The natural alternative to using Ethernet would be your LAN’s wifi, not Bluetooth.  Is that what you meant?

ONE SL

According to the profile, it’s a Sonos One SL, which does not have Bluetooth capabilities. When I want to send a Bluetooth signal to my Sonos devices that are not Bluetooth capable, I send it to my Sonos Roam, and then group the Roam’s room with the other Sonos rooms. 

I will explain what I’m trying to do. I would like to use my Sonos without a Wifi environment, i.e. use my Iphone + the Ipad ( I don’t have SIN card on Ipad).

Can my Iphone access the Sonos Roam?

Hard to do with the Sonos One SL, it’s not designed for that type of use. You’d be better off with a Sonos Roam, or Sonos Move, both of which are Bluetooth capable. The Roam could be grouped with other rooms, when you had WiFi, the Move not so much. 

Anything that you can do with the One SL wired by Ethernet, you can do wirelessly.  You cannot play content stored on an iPhone or iPad whether wired or wireless.  You can use the Sonos app on either device to stream content such as internet radio, Apple Music, Spotify etc.

Access? Without WiFi? Not really. Your iPhone can send a Bluetooth signal to an already set up Roam, though. But, as I say, it must be set up first on your home WiFi before it can be used via Bluetooth. 

Actually, you could use Airplay, but this does need a wifi environment.  But nothing needs an Ethernet connection..  If all you want to do is play without an Ethernet connection, no problem.  If you also want to do without WiFi, that is much more problematic.  Sonos is designed fundamentally as a networked system