In CX sections are supposed to be the same as in the source article. Nevertheless, translators sometimes want to add a new section. There is no way to add a section heading using the toolbar because the paragraph formatting button is intentionally removed.
It's possible to add them using ==, but even power users don't necessarily know this.
It would be nice to have VE's paragraph formatting button in CX2 as well, although perhaps it can be low-priority, for example behind a More (ellipsis) button.
Reported as part of Hebrew Wikipedia outreach. (T209270)