StackOverflow says that it can be done by editing xrdp.ini:
https://askubuntu.com/questions/133343/how-do-i-set-up-xrdp-session-that-reuses-an-existing-session#360835

Is there a specific reason for choosing RDP?
VNC is the most common protocol in Linux. And RustDesk is also a good, more advanced alternative.

Matrix (Element or other clients) seems to be the most popular one.

encourage people to help solve one of the issues that is keeping Lemmy from being an even more awesome alternative to Reddit:
https://popcar.bearblog.dev/lemmy-needs-to-fix-its-community-separation-problem/