Of course there is. On your capturing source you can set a filter like color-correction. There you are with brightness, contrast, gamma,...
But wait and rethink (just a moment) your question. If a camera is too bright, shouldn't you at first glance take down the gain or iso value, shorten the exposure/shutter time/speed to get it well-equally exposured at camera level before entering the computers world at all? Correcting later (at OBS stage) means you are loosing space to play with exposure, it will be shrinked and possibly distorted (completely flatten bright areas wih stripped and clipped colors).
Fixing exposure problems at camera level (and its driver) is always better than fixing it late in the process.