PSG face a combined Al Nassr and Al Hilal side on the 19th of January.
https://www.sportingnews.com/in/soccer/news/when-psg-vs-al-nassr-messi-ronaldo-date-time-schedule/mtxnggz1z5gk2j0rgyqybfwu
It's expected to be Ronaldo's debut. And possibly the last ever meeting with his great rival.