If you don't do it through a provider who does the informed consent route, they refer you to therapy initially AFAIK. FWIW I think it's worth trying the clinical route first (Planned Parenthood or otherwise) so that you have experience doing it "right" if your fears actually do come to pass. The federal political climate is a serious concern.
As for your parents, it's good to probe a little bit to know what their opinions are on various queer issues. They will probably try to support you in general, but based on what they know or how they perceive everything around them, they might try to "help" in harmful ways if they're like that. Are they baby boomers? Do they know what trans people are, and the difference (and overlap) between trans and gay? Do they believe in trans rights, or human rights more generally? Are they religious, conscientious, nationalist, liberal, or what? These are the kinds of things you should know about them before broaching the subject, and you can come out in stages if that seems better to you.