As others have said, there’s a great initiative currently underway with an effort to bring more public and random RP to The Crossroads as a hub.
Otherwise, since my return to the game towards the tail end of Shadowlands, I was able to take part in some evening RP in Orgrimmar’s Valley of Honor. It’s a smaller space than Stormwind, of course, with certainly fewer people but I didn’t have too much trouble finding RP when I had the itch!
It’s been a little while since I’ve been back there myself IC but when I’ve dropped by OOC I’ve still spotted RPers about, too. 
It’s definitely around! I don’t think we’ll ever see Stormwind numbers of walk-ups on Horde but they opportunities are definitely there.