Typical pro trimmers will happily chomp stuff up to the thickness of your thumb.
I had a garden to clear up 2 years ago. 40mx15m of 7ft high brambles, saplings and all sorts. I took my etesia pro56 mower, fired it up to max height and just drove it through the whole garden and cleared it to mulch in about 40 minutes.
The neighbour doffed his hat at me as I left.
I no longer have the white wonder, but would happily do this with a 30″ trimmer in a close domestic setting/windows everywhere. Mulch blades on a strimmer are for opening the throttle and covering yourself head to toe while the shrapnel flies everywhere.