Benefits vs risk of transmission fluid change (not flush)?

Background: Recently bought a beautiful used car w 134k miles. I previously could care less about how a car works, but now that I have my beauty, I’m almost obsessed with making sure she lasts. I keep reading suggestions to Drain and Fill transmission fluid, but my dad and husband (neither are mechanics) say DO NOT touch the transmission fluids. Can someone break it down to me and share your experience/ thoughts on this?! tia!