Just learn gain-staging already. It ought to be the first thing one learns.

 

Gain Staging: What It Is and How to Do It
www.izotope.com/en/learn/gain-staging-what-it-is-and-how-to-do-it.html

 

I think this is what you want:

https://letimix.com/products/gainmatch

 

Last edited: Apr 9, 2022

I use sometimes: " Brainworx - Masterdesk " www.plugin-alliance.com/en/products/bx_masterdesk.html

 

thats like asking someone to learn how to eat

 

True.
But still, some people don't learn it properly. They skip this important step.

 

It could be so simple, but we are musicians, are we? So we complicate things to be seen as extremely elaborated people...

Joking, of course.

In reaper, I do the folowing: mark the items/tracks/whatever, hit ctrl-alt-0 (means, I call a script called somewhat like "set everything selected to -18db RMS), let Reaper do it's thing, and bam... it's done. Gain staging the hard way. I do this always. As in always. Never ever think about gain staging again. "Gain staging" is one of the new buzz words. Forget it. Do it and be done with it.

 

PLOT TWIST - YOU ARE THE PLUGIN YOU SEEK

 

What for??? This equals 0VU in no way.

 

What you said is you want to 'automatically' normalize to -18 dB. You don't need any plugin for normalizing, any DAW or editor can do it natively, but you must use your hands still.
But gain staging entails a series of gain changes in FX chain, each gain change producing digital noise (digital rounding) - not a perfect way to avoid distortion.

 

Gain matching is not aimed at avoiding distortion, but at preventing our ears to fall into psychoacoustic trap.