With MoveAnything you can, as the name suggests, move, scale or hide basically every frame that exists in the interface.
The easiest way to scale certain elemts like the player frames is to open the MoveAnything menu via Esc > MoveAnything.
In your case you’re probably looking for Unit: Player > Player.
Click on the Frame Name (Player) to modify the frame. In the new window you’ll find the option Scale.
You’ll not have to change the scale of all the subframes like Player PVP Icon, Player Rest Icon, etc. as these should be scaled accordingly.