Anyway, you're on a Mac. Fix it yourself. Run the Shortcuts app and create a shortcut called something like "Maximize Preview". Set it to run an AppleScript:

  on run {input, parameters}
    tell application "Preview" to activate
    tell application "System Events" to set value of attribute "AXFullScreen" of front window of (first process whose frontmost is true) to true
    return input
  end run

Now in Shortcuts create an automation that runs when Preview is opened, and select that shortcut you just created as its action. You may have to go into System Settings > Privacy & Security > Accessibility and let Shortcuts and siriactionsd access to control your desktop.

Basically, you're doing something very uncommon for a Mac desktop, so it's not going to help you with that by default. It doesn't mean you're powerless to change it, though!