Dialing in espresso...
is a skill, but it's not rocket science. Once you figure out the basics on manipulating the time and output (basically just grind size) you can dig into flavor. Of course you'll never be able to change a coffee's overall flavor profile. If you have a darker roasted Colombian coffee, it'll never taste like a light roasted Ethiopian. Yet, what you can do is play with the things you can control.
For example if you like sweeter shots, try dialing in your espresso with less output, which is basically a ristretto. Same thing if you prefer more acidity, or mouthfeel. The thicker shot creates a very syrupy like texture. If you like your shots to be more balanced between the sweet and bitter run it longer, more like a traditional espresso shot. This creates a thinner texture, but allows for more the nuanced flavors come through. If your espresso is very complex then I'd definitely recommend this style of shot.
In this video I take a Fancy Kona from The Roasting Plant which has a more mild flavor profile and show how I toy with the grind size (which changes extraction time) and output to create a more acidic, sweeter shot, which is more towards my preferences. Of course this works both ways. I highly encourage you to do some playing around with your favorite coffees and see what kind of different flavors, acidity, or sweetness you can get. It never ceases to amaze me how different coffees can taste with incremental changes in grind size (i.e. extraction time) and output amount. Of course not all will be good, but it will increase your understanding of extraction and flavor development through brewing.