SEO for One Page Site

So I have a possible client that has a newish (7 months old) single page site (no pagination) and I have never done any SEO on a one pager. The site is mobile friendly and has a 99% page speed score for both mobile and 100% full size.

How hard is it to rank for multiple related terms/sections? Section 1, Section 2, etc. Is this going to be a huge headache or is it doable with out much headache?

Any tips would be greatly appreciated.