This can easily become the biggest section of this website. This is why it is so much fun, you can try out very different things and test out whether it improves your result or not, and if you can taste a difference.
For sure there is a break even point where more equipment will not help anymore, but from my point of view this really depends on your budget (just kidding) willingness to put effort into a single shot, aspirations and most importantly your coffee beans. If you are not into the most complex micro-lot beans, you might not need fifteen filters and screens. On the other hand some things really make sense and influence your shot in a way that you cannot leave them out anymore, e.g. using a WDT and drawing toddler paintings in your coffee puck really has an influence on the extraction time, so you have to stick to it or you have to change your grinder settings every time.
Tbc