Is it possible to create an arc which connects to 3 elements tangentially? e.g. an arc between elements but the centre point also touches a third element in the middle. Something you can do in AutoCAD with Circle > 3P > tan snap for each point.
I've attached an example in red of it in AutoCAD.
Yes, this is easy with simple drawing tools. Just use the Place Arc command and Start/End/Mid or Start/Mid/End and use the tangent snap.
Or... if you want intelligent horizontal geometry, you can also do it with the Arc Between Elements tool and the same tangent snap.