Can do Havdalah this year on Rosh Hashanah 2020/5780 in Motzei Shabat, who lives in galut?
For Rosh Hashana even those living in Eretz Yisroel have two days of Yom Tov. When Yom Tov is on Motzei Shabbos, we say a special kiddush which adds a bracha for בורא מאורי האש and another special bracha for havdalah between Shabbos and Yom Tov. You can find the text in your machzor..
A kasiva v’chasima tova