Whatever said by Filter, that's true. You can add tp, sl or can close the positions also. But after closed the position, same order will be open to match with signal provider's account. So, no benefit.
You can check from your end easily to get more knowledge about signal activities, if you really interested to follow the signal.
Open an demo account and subscribe a signal which is for demo, then you can apply your all the questions to demo account and get the actual result.
Wish you best of luck.