I Think youYou can use Arcade to create an expression.
I dont really know what im doing (first time using Arcade). Just pasted the code from: VxCount = !shape!.pointcount fuction in AGOL and modified last line to output 0 for even number of vertices and 1 for odd. You can of course change this to output whatever value you want with some if/else:
Function CountVertices(geom) {
var cnt_vertices = Null;
var geom_type = TypeOf(geom);
Console(geom_type);
if (geom_type == "Point") {
cnt_vertices = 1;
} else if (geom_type == "Multipoint") {
cnt_vertices = Count(geom.points);
} else if (geom_type == "Polyline") {
var cnt_line = 0;
for (var i = 0; i < Count(geom.paths); i++) {
cnt_line += Count(geom.paths[i]);
}
cnt_vertices = cnt_line;
} else if (geom_type == "Polygon") {
var cnt_pol = 0;
for (var i = 0; i < Count(geom.rings); i++) {
cnt_pol += Count(geom.rings[i]);
}
cnt_vertices = cnt_pol;
} else {
// this should not happen...
}
return cnt_vertices;
}
return (CountVertices(Geometry($feature))-1)%2