If it helps, I'm running Win11 Pro (direct install from MSFT ISO) on my 2019 MBP using the standard desktop version of Parallels 17. I tested 18 when it was new and it came with Win11 Pro, but I don't recall if it was a trial license or not. Going off my my Current installed version of Parallels, I can say that installation is pretty straightforward using the popup interface or the File menu (New...). Then choose "Install Windows or another OS" that has the icon with CDs / USBs on it. From there, point it to the ISO you downloaded from MSFT or had available. I'm not really using it right now, so the space used is minimal, but it's currently taking up 50.05 Gb with only the raw OS that is current on updates (no other software installed, but the OS wasn't stripped either). Oh and you have to use v17+ of Parallels in order to get the TPM module added in settings (will need to do That before going further or OS installer will complain).
From what I've read on threads here for Win11 on Silicone, it gives the option to install Win11 Pro just like for me, but it's the ARM version of the OS due to the inability of Parallels (or any app I'm aware of) to mimic / translate the x86 platform, so you'll either have to use the pre-made VM from Parallels v18 or get ahold of the Enterprise version of it as the only other alternative is to use the Developer / Beta version from MSFT (licensing issue). I don't think that you can activate the latter either without the Enterprise version. I've also read on here that the Win11 VM people install on Silicone has a set capacity of (up to) 256 Gb, but there are many threads of people trying to fix some issue where the VM suddenly takes up a ton of Host disk space.
Personally, due probably in part to the restrictions from Apple, Parallels on Silicone is not as helpful for VMs as it is on Intel due to the platform's differences. Even MacOS Guests are restricted to needing a specific Host version in order to run the one you want. I think the only OSes you can run are Monterey and newer, but you have to have a Host with the same or newer OS IIRC, so kinda pointless to me. Windows is worse because of the x86 to ARM issues many have that will only continue unless MSFTs licensing changes and they, again, work with Apple to make drivers. There is no bootcamp on Silicone for that reason.