Fabfilter make some tremendous plugins for mixing, mastering and recording - many of which are endorsed and used by the biggest artists in the industry. In this video, Dan Worrall gives an in-depth explanation of levels and loudness in the digital domain - and what affect the increasing of loudness can have. Pro L2 is one of their flagship products for loudness, which is demonstrated in the video.
In this part one he asks the questions: Is louder always better? How can you make your audio sound loud and still have depth and punch? Fabfilter currently have a summer sale with 25% off anything in their store: https://www.fabfilter.com/