There are a few different ways of resetting passwords via the password reset page.
You can send an email directly via the password change endpoint, or you can generate a link to the page via the password ticket endpoint. The ticket gives the power of password reset to whoever holds it, and should be used carefully. The password change endpoint is basically the same as the user clicking the “i forgot my password” link and submitting their email.
Take a look at this doc that explains it all:
There is no way to open directly to the password reset page because the user hasn’t authenticated in any way.