Do native English speakers sometimes pronounce "/ɒf/(off)" as "/əf/", according to the schwa rule?

Do native English speakers sometimes pronounce "/?f/(off)" as "/?f/", according to the schwa rule?

I've already looked up the word "off" to check whether it can be pronounced according to the schwa rule, but I couldn't find any dictionaries it can be pronounced as /?f/. I think it can be pronounced like that, but I've once learnt that any prepositions can be pronounced according to the schwa rule, but it seems like I learnt wrong and only some prepositions can be. Are there prepositions that cannot be pronounced according to the schwa rule?