If you’re interested in event-based RP, look for event and campaign threads on this forum and check out the Wyrmrest Community Project and RP Event Collection Discord servers. There are a lot of events being run and many (maybe most?) are neutral/cross-faction accessible.
If you’re looking for random walk-up RP, go to Duskwood, not Stormwind. If you have TRP3, you can use the map-scan button in the lower left corner of your zone map to find other people who have TRP3 (as long as they don’t have that function turned off). This can help with figuring out where people are hanging out on a given evening. Remember that the /who command is broken and may not tell you that people are there even when they are.
I saw you made it into the WCP Discord already, Chuwen! Welcome back to WoW!