You cannot create a bootable macOS 10.11 USB installer using Ventura unless you have already extracted the real macOS installer from the downloaded .dmg file. To actually extract the real installer requires using a Qualifying Mac which is compatible with macOS 10.11 as the .pkg extractor app will not run on any other Mac, except one compatible with macOS 10.11. Read the instructions very carefully:
Create a bootable installer for macOS - Apple Support
Apple moved the instructions for macOS 10.11 to the "Download macOS" link in the previous article:
How to download macOS - Apple Support
Step #3 in the "How to download macOS" article is the critical step you missed.
1.Double-click the .pkg file, then follow the onscreen instructions. This installs the macOS installer into your Applications folder.
FYI, a 2019 Mac is not able to run the .pkg extractor app. Generally a Qualifying Mac for macOS 10.11 is one from 2008 to 2015, but you can check which Macs are compatible with macOS 10.11 in this article:
https://eshop.macsales.com/guides/Mac_OS_X_Compatibility
At one time I did have a link to instructions for using the command line to manually extract some files from the .pkg extractor app in order to create a bootable macOS 10.11 USB installer, but later comments indicated that Apple changed something although someone did manage to modify the instructions. I have no idea if the instructions will work with the current download. Besides, the instructions were very long & complicated even for someone who is familiar with using the command line. Many average users would probably not be successful in following the instructions as there are a few steps which are a bit confusing.
Unfortunately I am not aware of any other way of creating a bootable macOS 10.11 USB installer than using Apple's official instructions and a Qualifying Mac. Now if you had an extracted copy of the real installer app, then you could use the command mentioned in your post (at least on an Intel Mac, it will not work on an Apple Silicon Mac). I don't know why Apple has to make something like this so difficult.
