Putting it simply tricep pulldowns will not do much in terms of muscle growth! I see a lot of guys doing fancy stuff such as laying extensions, ropepulldowns, standing, overhead, far bar etc. This will not build bigger triceps!!
It will give you a good ‘pump’ and take a great photo but it will not lead to great gains in size.
I mainly have my clients doing 1 if not any isolation work on triceps.
So these are the exercises that will lead to greater gains in size and strength to your triceps
Close grip presses
Dead stop skull crushers (fav iso exercise)
Close grip push ups
My advice would be pick 1 or 2 of these exercises on upper or push days and perform to sets one set of 8-10 and one set of 8-12
Progress the weight each week!!!