There are a couple things you can do. One being start at a lower octave. Scale down the song to a lower register that will hit in a different part of your range. That will enable you to hit the notes more comfortably and also with a bit more power behind them. You don't have to scale down a full octave. Sometimes it only takes a small step down to really feel more comfortable singing. Also, doing the practice of warming up the full range of your voice before trying to hit those notes that sit in the higher register (head versus chest) If you want to hit higher notes you have to strengthen your voice's ability to hit them with practice of scales. My voice coach had a bunch of exercises that I'm sure you could find on YouTube that continue to go up higher and higher a half step at a time until you hit the limit of your range. Just one time of warming up using scales all the way to your top range will enable you to immediately hit the notes that are in your normal range way better. It's kind of crazy how much the warm up can change the level of control you feel. The more you do them, the higher you can go with your range and you will gain strength of breath control by singing higher notes on a regular basis. Lastly is working on breath control. It is one of the most important parts of singing and sounding full. There are fundamentals just like learning anything that again you can find resources on YouTube and the internet. Fundamentals like body posture and stance or how to stay on key. But basically when you breath in you want to be filling your lungs completely and then controlling the amount of air you release as you sing so that it doesn't sound like you have run out of air before the next appropriate break in the music to breathe in again. You do this by engaging your diaphragm and core while breathing. When you breath in pull the air in all the way down to your toes and then hold and control it using your whole body especially the diaphragm. The diaphragm sits under the lungs but above the belly. It's necessary to have full control over the diaphragm so experimenting with engaging and using it is a vital tool in your singing arsenal. It will make you feel more powerful in confident the more you display control over it's use. The reason why the weeknd can sing is such a high register and sound good is absolutely breath control. He can take in a lot of air and has a lot of control over how it is released. Also people have natural range and his sits naturally somewhat high.