There are several affordable apps available to help writers self-edit, like Grammarly and ProwritingAid among others. They all more or less do the same things but some are a little more user friendly than others.
I tried Grammarly, for example, and found it too invasive and annoying. That's why I use ProwritingAid, but I learned quickly that if I just followed what the app suggested, my writing would look like soup. You have to be smart about any of these apps, and trust your own instincts.
The best way to show you how to use PRowritingAid effectively and efficiently is to show you the demo and exactly how I use it for the "heavy edits" in my own writing. In this demo shown here, I walk you through a piece of my draft novel and illustrate the most important tools to use.
If you'd like to try this app out for free, just click this link and sign up.