You can always stop and call for help.

Don’t do anything you aren’t trained to do, and always ask “can I help?” / get verbal consent if they are conscious.

The danger is just if you have bad judgement. Say you saw a tourniquet on a TV show so you think you know when it’s appropriate to use a tourniquet - or if someone is injured and you decide to move them which makes them MORE injured. (Note: you CAN move them away from a fire or something that would otherwise kill them. “More injuries” is better than dead.)

But you can ALWAYS stop and be kind and call for help and wait with them!

If you act in good faith and aren’t trying to “play doctor” when you aren’t one - no jury is going to punish you for that. If there aren’t good Samaritan laws in your state (there are in most) they might be able to take you to court but they won’t win.