In MacOS Sequoia, is there a way to lock windows into a Split View-like fullscreen mode but with more layout flexibility?

[All images referenced below](https://imgur.com/a/QfmJe8s) I rely on Spaces and fullscreen mode to avoid visual clutter, distractions, and the weird anxious feeling that loose application windows give me for some reason. The downside is that most windows and apps aren't really designed to be fullscreen width—they become really hard to read because the content goes edge to edge [(image #1: screenshot of Messages fullscreen as an example)](https://imgur.com/ikpHK5P). As a comparison, I love Sunsama's daily task list view in fullscreen [(image #2)](https://imgur.com/ytdfDFm) because it embraces blank space on each side of the active content. I've also used an iPhone/iPad app that wasn't available for Mac on my laptop and the fullscreen narrow portrait mode interface with black margins on either side was very close to how I wish I could use most Mac apps fullscreen. **What I'm looking for** In MacOS Sequoia, is there a way to lock windows into a Split View-like fullscreen mode but with more layout flexibility? Examples might be: * locking a single window fullscreen height and 50% width like Split View, but centered with the ability to customize how the margin on each side is treated *(*[Image #3](https://imgur.com/PcsZPNS) *and* [image #4:](https://imgur.com/4ItFvPK) *mockups of how I wish I could set Messages* and other apps *to look fullscreen)* * locking more than 2 windows side by side in different configurations than Split Screen supports (1 half screen on the left, 2 tiled on the right vertically, 2x2, etc.) * locking a window on a portion of the screen but being able to use the remainder of the screen as usual without accidentally covering, moving, or losing something under the locked window (like Pin Mode in Rectangle Pro, but full-screen so it's not loosey goosey). **My system** Macbook Pro 2023 with M2 Max running Sequoia 15.2 (24C101) **What I've tried already** * Mac OS Sequoia 15.2's new native window tiling (it's nice for loose windows but doesn't "lock" them in place like Split View does) * Window management apps like Magnet and Rectangle Pro (seems like they have limited full screen capabilities since fullscreen + split view modes are managed by Mac OS Spaces) * Dimming apps like HazeOver that reduce visual noise around loose windows (also helpful when working with many loose windows but doesn't seem to offer additional full screen functionality)