Yeah, I was lucky enough to get in on the constant height bandwagon before my daughter was born, many years ago. Had the disposable income then to purchase a Stewart, 2.40:1 aspect ratio screen, and have been using various projectors (CRT and DLP with an anamorphic lens) over the years to show movies in that authentic experience. 
Love it and wouldn’t want to go back watching Scope movies in a 16x9 window with letterboxing visible.
I used to re-encode all my movies to reduce the size, back in the day. Now with storage prices being so cheap (especially if you are willing to use HDs pulled from data centers), I built an unraid server and rip and remux. Faster, and maintains quality. I sometimes have a smaller 1080p file for use on smaller TVs in the house, no point in having Plex beat up when my daughter wants to watch something in her room.
It also helps that I buy much fewer movies than back in the day. I only go after the ones I really enjoy (like the MCU movies) and then stream the rest via Netflix, Disney +, Amazon prime.
Here is the feature request thread on this topic: Aspect Ratio
I didn’t go into as much detail in that thread, but would be happy to do so, if someone thought it would help.
