ArcGIS Online Web Map change label font, color, weight, etc... with Arcade?

[FrankMancini]

Is it possible to set the properties of labels in ArcGIS Online web maps using a custom expression?

Any way similar to adding tags like in the ArcPro examples? Text formatting tags—ArcGIS Pro | ArcGIS Desktop 

Saw this Arcade Label example ( Arcade | ArcGIS API for JavaScript 4.9 ), but couldn't figure out how to make it work in a WebMap Custom Label Expression.

Any ideas?

[RezaTehranifar2]

I am running 10.7 portal and making a webmap where I would like to label outside of what is provided in the pallate.

Just curious. Is it worth trying to change the label color in AGO assist? Has it been confirmed that changing the label color using that service work or not? AGO Assist can be mixed bag...