how does danny phantom control when he “goes ghost” anyway like is it a thing he can do simply by force of will or does it just happen whenever he clenches both his fists and makes a serious face
It’s connected to his emotions. Early on when he was still trying to figure it out, he would lose control of his powers and become intangible when stressed or angry but he eventually learned how to control his powers.
Hell, he was super scared when he figured out how to do his banshee scream because he was stuck in the future where all the ghosts wanted him uber dead and he killed his family and became a villain.