In theory you should be able to boot into Recovery Mode using Command + R, but this will boot to the local recovery volume if it exists, otherwise it will try to boot into Internet Recovery Mode which in theory should boot into the macOS 11.x Big Sur installer, but could equally boot into the installer for the original OS.
You can erase the physical SSD by booting into Internet Recovery Mode (Command + Option + R) for the online macOS 12.x Monterey installer. You can use Disk Utility to erase the physical SSD, but within Disk Utility you may first need to click "View" and select "Show All Devices" before the physical SSD appears on the left pane of Disk Utility. Unless you can boot into the online Big Sur installer, then this won't really benefit you since you don't have a bootable macOS 11.x Big Sur USB installer (In theory you should be able to boot Big Sur online installer, but unfortunately it does not always go as planned).
For creating a macOS USB installer... unfortunately you need access to another Qualifying Mac to create a bootable macOS USB 10.13+ USB installer. A Qualifying Mac would be one from Late-2009 to 2020 which can be used for a macOS 10.13 or 11.x USB installer (Late-2009 to 2018 for 10.13, or Late-2013 to 2020 for v11.x).
How to create a bootable installer for macOS - Apple Support
https://eshop.macsales.com/guides/Mac_OS_X_Compatibility
There are instructions for attempting to manually update the laptop's system firmware to allow macOS Monterey installer to work with a third party SSD, but it does require a system firmware level of at least 195.0.0.0.0+ IIRC (use at your own risk):
https://tinyapps.org/blog/202110270700_monterey-third-party-ssd.html
Edit: Another option is to install macOS to an external USB3 SSD. This would allow you to install the original factory OS which then would allow you access to create a bootable macOS USB installer for the desired version of macOS 10.13+.