"Currently not ..."
Different font (sizes) would be a fundamental change to SynEdit.
SynEdit is meant as an editor, not word processor. It is optimized for this.
Adding those feature is likely (not necessarily, but likely) having huge performance impact. In that case it may be that the decision goes for 2 branches, keeping the editor, and creating a text processor.
But I may be wrong, that is to be seen if an actual implementation surfaces.
left right center....
Without line wrapping, I only see a point to have the entire text left or right. That would also be good for RTL text)
With wrap, the wrapper can influence how the text is shown.