As of now, the only way that I know of to style “tags” in the Properties view are all the values of one Property type. (Towards the end of Properties view CSS - The Fall Collection). A rough example:
.metadata-property[data-property-key="aliases"] .multi-select-pill {
background: green;
color: yellow;
}
.metadata-property[data-property-key="tags"] .multi-select-pill {
background: orange;
color: blue;
}