Emissive Influence & Bloom
You might notice that as you increase the strength of your Emissive input inside your Material Instance, the bloom that is generated from the Emissive sections of the Material will get brighter and brighter.
One way to tone down the effect of the Bloom without turning down the values inside of your Material Instance is to adjust the Bloom setting on the Post Process Volume.
Adjusting this value will help to compensate when you push the Emissive values very high to get more static light from the Emissive Material cast in the world. In the image below, on the left-hand side, you can see what happens
when the Emissive value is pushed to a very high number, 100, and the Bloom is not adjusted for. In the image on the right-hand side, the Bloom setting was tweaked from 1 to 0.1.
This will still allow the Emissive to cast lots of static light into the world and also not blow out the Bloom.