Here, try this out. It has a feature that lets you stretch to 16:9, 4:3, and 3:2, and crop to 3:2, 16:9, and 24:10. If you want to install the crx extension, you'll have to unzip it and load it as an unpacked extension. Once it's installed, look for "Aspect" under the video.
I use the one that is built into Chrome (version 75+). To activate it go to chrome://flags/#enable-reader-mode and enable it then restart.
How to enable Google Chrome's secret ‘reader mode’ for distraction-free reading