Jhanas, breathwork, psychedelics, MDMA, etc are all tools to for inducing altered states, from which new insights can arise. None of the actual methods matter, so much as putting your brain into what I think of as “developer mode,” from which you can write new rules that govern your thoughts and behavior, then close things up and operate anew. (Some people call this “neural annealing.”)
The biggest impact of these kind of tools/experiences is understanding more about how your brain operates and how it could operate. And seeing how happy you already are and how attention almost completely controls your experience of it.
Rob Burbea had a retreat focusing on the jhanas that’s truly excellent.