You have to get script access added by the admin – so for one client I had to beg for it – but since jQuery is part of Sharepoint – all we do is add some code and it makes the items between <h2> tags appear and disappear. Add a little more CSS to get a + and – added to the right and we are good to go. I would use a different <hX> or make my own – but Credit goes to this guy:

https://info.summit7systems.com/blog/how-to-create-dynamic-accordions-in-sharepoint-pages