Yes, it is extremely cumbersome. And iOS 13 changes nothing to it. Reachability looks like the obvious solution, but I would argue triggering reachability is equally cumbersome if not even more in one hand. And because the thumb has to be so stretched down, I almost dropped my iPhone XS Max while trying to trigger reachability.
After a few tries, Apple is expecting people to use their phones with right hand most of the time, not left hand. I have no idea what is the reason behind it, and I don’t see Apple using the other top side for anything else. Maybe if they introduce an iPhone with grip detection, they can introduce a feature in iOS to support control Center pull down position. Or better yet, make a setting similar to Apple Watch wrist adjustment setting for control Center.