Can I make outgoing calls on iPhone with SOS mode

Only emergency calls – i.e., to the police, fire department, or ambulance service. Not to friends, family, or anybody else.

The SOS indicator means that you either don't have a cellular plan, or aren't within range of your carrier's network – but that you can make emergency calls using other carriers' networks. Some countries require phone companies to put through emergency ("life and death") calls whether the person making the call has service with them, or not.

You ask 2 different questions. First, can I make outgoing calls on iPhone with SOS mode. To that, what you have gotten from others is correct, you can only call emergency services. In the text of your question, you ask "If my phone is off, can I still call people" The answer to that is No. If your iPhone is powered off, even if you had cellular service you couldn't call anyone. Nothing works on the phone when it is powered off.

No, you cant make or receive phone calls if your phone is off or in SOS mode. SOS mode means you cant connect to your carrier's cell service. You need to contact your carrier and work this out with them.

If you see SOS, No Service, or Searching on your iPhone or iPad - Apple Support

No. the only call you can make is to emergency services.

can I still call people

You should be able to call the people at 911