going to the sweetener tour alone Watch
It'll be night time and there will be about 20000 people all spilling out of the arena trying to get home. It'll be impossible to get an uber/taxi, and since the roads will be filled up it'll be difficult for the person who's picking you up to drive close to the arena.
I'd suggest leaving about 10-15 minutes early and arranging a place to meet your parents afterwards. Make sure your phone is on a high percentage too.
Other than that i'm sure you'll be fine and have fun