The system product name is the model name of your Windows 11 device.
An OEM will usually specify the system product name (ex: "Surface Pro X"), and usually cannot be changed.
If you built the PC yourself, then there usually isn't a system product name specified allowing you to change the default System Product Name displayed to a custom name you want instead.
This tutorial will show you how to change the system product name in Windows 11.
You must be signed in as an administrator to change the system product name.
EXAMPLE: System Product Name
Open Registry Editor (regedit.exe).
Navigate to the key below in the left pane of Registry Editor. (see screenshot below)
In the right pane of the OEMInformation key, double click/tap on the Model string value (REG_SZ) to modify it. (see screenshot above)
If you don't have a Model string value, right click or press and hold on an empty space in the right pane of the OEMInformation key, click/tap on New, click/tap on String Value, type Model for the name, and press Enter.
Type a system product name you want, and click/tap on OK. (see screenshot below)
You can now close Registry Editor if you like.