Is it possible to update the’ position/rotation of an object in a running game by setting its properties in the editor. In other words, when I change something in Unreal editor I’d like to see it change immediately in a running instance of the game.
The editor settings such as position/rotation are part of the initialisation for the class I believe, so they do not update live, they apply themselves at Begin Play, with the exception of Simulate mode. If you run in Simulate you can change your settings in realtime. If you make changes in Simulate mode you can press K to bake them as the new defaults so when you exit Simulate it keeps them.
As an alternative you could always make a little Developer UI with UMG which would let you change those stats. It would only apply in-game and would be lost on exit though.
Lastly, and this is riskier, you can enable some more powerful editing during game, you need to go into your Editor preferences>Experimental>AllowEditingOfPotentiallyUnsafeProperties. Iv had this on for some debugging but not tried forcing changes through it. Completely up to you if you want to try that.