I use the TC Electronic Clarity M
It has a plugin, but can also be used by sources plugged in, ie AES.
But I also use Insight 2 (from iZotope) and Youlean Loudness Meter (which is free). Steinberg also includes SuperVision in Cubase/Nuendo which is much the same.
https://steinberg.help/nuendo_plugin_reference/v11/en/_shared/topics/plug_ref/supervision/supervision_r.html