Can't say I was a narcissist, but I had an epiphany at one point about "being too full of myself" as well as taking over conversations too often. I really dug into certain philosophies to help course correct.

The most useful philosophies (for me) were/are Secular Humanism and Utilitarianism PLUS all of the sub-philosophies inside of each. There are definitely some problematic ideas in each, but I think you'll gain some new perspectives.

There are other areas to look at, but what I listed is a good start. Stoicism can also help with emotional control and being more aware of your thinking. It's kind of like a "practice".

You can buy books or browse the web for this stuff, of course.

NOTE: I have ZERO credentials in philosophy... it's just my hobby. However, I don't think my recommendations here are out-of-line as they are pretty high level. Would love to have more seasoned folks comment/point out other areas of philosophy that are useful in gaining insights for the OP's issues.