Open up regedit, and go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths

Create a new key named cmd.exe and set its default value to the path where you've installed your Windows Terminal.

This makes use of an alias to launch Windows Terminal instead of cmd.exe

Doing this will allow you to launch Windows Terminal when you type cmd or cmd.exe in Start, Run dialog in Windows. If you run cmd in a terminal, it will still launch cmd.exe instead of wt.exe

Also, if you want to click the Command Prompt icon (from the menu) to launch Windows Terminal, just update the shortcut to launch Windows Terminal instead.

And, if you want to type cmd in PowerShell and launch Windows Terminal as well, set up an alias, like so:

Set-Alias -Name cmd -Value "C:\Program Files\WindowsApps\Microsoft.WindowsTerminal_1.15.2874.0_x64__8wekyb3d8bbwe\wt.exe"

Note that if you update your Windows Terminal to a new version, you'll need to redo all the above with the updated location of the new version.