How can I make my mic stronger when it comes to long powerful high notes? For example the ending of Santa Fe

Hi, Gavin! More power can come from increased compression (AKA vocal effort) and/or increased breath support/air resistance. The two go hand in hand, in my experience! 

Make sure you're adding power with increased bodily engagement, not increased "squeezing" or "pushing" from your throat. The gentle "pushing out" feeling in your low abdomen (of your normal “breath support”) can intensify to a little more of a "lean" or "slight grunt" feeling. The important word is “slight”: we do not want to squeeze or lock up the abdomen! 

The other thing you can play with is brighter, more forward resonance - that's not necessarily power, but it does sound louder and can be perceived as more powerful.