scaleExpression property
An arcade expression object with an expression for scaling symbols in a dictionary renderer.
The ArcadeExpression is evaluated at rendering time. If the expression
is not valid or results in an invalid value, symbols will not be scaled
and will display at their original size. For example, to scale symbols
based on an attribute value, you can set ArcadeExpression.expression as
follows. This expression if($feature.Symbol_Set == 40, 2.5, 1) scales the symbol size 2.5 times when symbol_set is 40.