@JohnAtl’S mention of Latex (no attempt on my part at formatting that properly) 
made me go back and read the original post.
The OP mentioned Pages. I don’t know what format you can type into Pages - whether RTF or HTML or (unlikely) Markdown.
The issue to me is not what bytes you can coax TextExpander into emitting but rather what bytes would be useful from the Pages POV.
(I don’t use Pages so don’t know the answer to that one. Anyone?)