This is a simple question probably asked before, but can you make the linux torbrowser launcher, install an older version of torbrowser? The torbrowser launcher settings give no option to do this, so it just installs the latest. Regardless of older versions having more bugs and vulnerabilities, you can install the older versions manually, but this doesn't seem the same as when it is installed using the launcher.
That's not possible unless you were to hack the code of torbrowser-launcher yourself. The reason for that is because every new version includes code fixes to help ensure your anonymity online. Using an old version would make yourself more at risk.
However, it's your computer and you can do with it as you like. Here is the original github if you want to tinker with it.
Basically, you'll never need it: because new versions are containing not just some improvements, but also a security fixes, so "the last is a must". However, if you need to test some on the real old code - the best, but not the easiest way - is to set up your CI/CD like Jenkins and to pinpoint a spot where you want to freeze the code precisely. After that - just build it and here you go. This approach also fixes the issue if there's no pre-built binary for your system/setup or if it has some issues. Old releases of the launcher will and has to pull the tool for the latest version - that's what it's built for, so that's why there's no command line switch for that kind of behavior