Forms with conditional sections – Accessibility

Business banking space. I have a very long form, broken into multiple sections, across several pages, with Save, etc.

We only support Eng and Fre as languages. But the business could be anywhere, so we can't assume one phone format.

Some pages of the form have yes/no questions that drive whole sub-sections to appear. eg. if you check 'I am in school' box, you will be required to fill out several more fields about your school. (This would occur on the same page, not a separate page).

I am mindful of the need to not mess with context for visually-impaired users.

Is it all right to have the subsection hidden or collapsed until the user checks the box, and then it expands? How will a screen reader deal with that?