I dont think so if LMMS have. I tried Youlean Loudness Meter and works very fine at LMMS and Audacity
edit: I used it as a VST 2 Plugin and I put it on the master chain
edit 2:
Put the dll file on the vst directory specified in your lmms settings
Close lmms if you installed it while lmms is running.
Now open lmms
in the master chain #0, click add effect. there, search "youlean loudness..."
It should work now. You do not need to drag audio. It will automatically start scanning the audio once you play the song.
Another great mastering plug in you can partner is Limiter no.6 by Vladgsounds. Place it before the Youlean plug in (so Youlean can detect Limiter no. 6's signals). Effectively adjusts true peak without changing volume and the best limiter out there.