This has been mentioned a few times. For example:

1. There doesn't seem to be a way to have something for max line width. Perhaps leveraging the softline captures to tell the formatter that it's ok to wrap long lines of code across multiple lines without requiring the developer to multiline first?

That's right; Topiary has no concept of line-length and using that as a constraint to force reflowing, like other formatters do. I'm not sure if this is "by design" or "by accident", but the general nature of Topiary means that it's not obvious how to wrap long lines in all cases.

Originally posted in #699 (review)

Per the comment, Topiary currently doesn't do anything with long-lines. It would be worth investigating whether anything suitably general can be done (e.g., forcing multiline mode at a certain column, etc.).