Creo Elements/Direct Modeling 21.0 release plan is 2018.3 referring http://support.ptc.com/cs/product_calendar/PTC_Product_Calendar.htm.
But there is few enhancements in V20.0 referring to https://support.ptc.com/appserver/cs/view/solution.jsp?n=CS237747. Hope will add more enhancements into V21.0