You will need to create an object Fontand pass it to a property Fontin the label control.
Unfortunately, with these objects you need to give a few things in the constructor, so you cannot just create an empty object and fill it with such details as you can with a label.
For this purpose, you can do this before adding a control to your form:
$LabelComputer.Font = [System.Drawing.Font]::new("Microsoft Sans Serif", 12, [System.Drawing.FontStyle]::Bold)
, new(...) :
.
: , $LabelFont, $LabelComputer.Font = $LabelFont.