Is there a command for
footmisc similar to
\sisetup for setting options in another way than via
I can't find anything in the manual.
No, there isn't any other way for selecting options other than passing them at loading time.
The package redefines several commands and it wouldn't make sense to change the setup mid document. Perhaps there could be an interface for
symbol*, but playing with the options that change the formatting or placement of footnotes mid document would most certainly make LaTeX crash disgracefully.