Og was Noachs slave Pirkei derav Eliezer 23:
וישאר אך נח ואשר אתו בתבה וחוץ מעוג מלך הבשן שישב לו עץ אחד מן הסולמות של התיבה ונשבע לנח ולבניו שיהיה להם עבד עולם
The only other other survivors of the flood except Noach and his family were Og and acccoring to tosfos Niddah 61b Sichon also survived as he was Ogs brother and pair mentioned in Gemara Niddah 61b. Alternatively the Rosh says Ogs mother survived and Sichon was born after the flood as every pair was male and female. See Nephilim after the Flood.
Og and his Mother/brother were freed after the flood see https://www.sefaria.org/Pirkei_DeRabbi_Eliezer.16?lang=bi which paved the way to Og's Kingship of Bashan. So Sichon is decended from Og's Mother, and Devarim 2,33 mentions that Sichon had a son :וַנַּ֥ךְ אֹת֛וֹ וְאֶת־בנו [בָּנָ֖יו] וְאֶת־כָּל־עַמּֽוֹ, and since Both Sichon and Og's people Confronted the Israelites with war and were all killed, there are no living descendants nowadays.