It makes everything look washed out and lifeless. Too many artifacts and grain. I hate it very much. The iPhone X did much better everything looked balanced.
Download an app that shoots RAW. This is your only option.
As for videos - I think it's impossible. The only thing you can do is to again download a 3rd party app that lets you shoot at the maximum possible bitrate - 125MB I think it was (vs. 50 or 75 on the stock camera app, I'm not sure). But they're all paid.
Looking washed out and lifeless is a rare complaint. You might want to look at your images on a different screen/monitor and see if they still look bad. If they do, check the camera settings for HDR and preserve original image. If they don’t, maybe a screen issue? Try setting truetone to something different, adjusting brightness, etc.