The cantrip Control Flames has a list of effects it can do: four items, out of which two are instantaneous, and two are non-instantaneous. One of the non-instantaneous effects listed there is:
You double or halve the area of bright light and dim light cast by the flame, change its color, or both. The change lasts for 1 hour.
It also states:
If you cast this spell multiple times, you can have up to three of its non-instantaneous effects active at a time, and you can dismiss
such an effect as an action.
A torch can shed bright light for 20ft and dim light for another 20ft. So, simply, can a torch that has been cast with Control Flame thrice shine for 160ft of bright light, and another 160ft of dim light?
Best Answer
My understanding of control flame is that you can have up to 3 of its effects as stated in the spell description. To my knowledge and as stated on P205 of the PHB same spell effects do not stack.
So in answer to your question, no you cannot make a torch shed light for 160ft of light. You could however for example expand the flame, double the brightness and manipulate it all in the castings.