Differentiate between single click and mouse hold

Hi, i’m new to unity, so i apologize for the dumb question.
i’m trying to make a 2d space game, where if i click once the starship shoots, while if i hold the mouse button it slows down, the problem i’m having is that if i held the mouse button the ship will both shoot and slow down, is there a way to make the GetMouseButtonDown return false if the mouse is being held?

if (Input.GetMouseButton(0))
Debug.Log(“Pressed left click.”);

returns true all the time you’re clicking the mouse button and will end if you release the mouse button.
so just put your shooting script here and put your slow down script or any script that you wan to only work once inside the Input.GetMouseButtonDown