Yeah, of course Reaper also supports all types of plugins, including of course all types of VSTs (32 or 64 bits), and DX, LV2, etc.
But sometimes the thing that you need does not exist. I needed a "MIDI notes compressor" and couldn't find one, so I wrote it (the compressor brings all notes to a chosen range, so for example if the range is A3-A5, a C7 will be converted to C4).
You could just use any of the thousands of VST plugins out there, which Ardour fully supports.