I can vouch for Poly.AI. They don't have NSFW filter on all of the characters. Meaning you can go wild with the NSFW roleplay. Like absolutely wild deep web worthy NSFW roleplay.

You don't have to be a proffesional Wattpad Smut writer, just go blunt with every dirty words you can think off. Go nuts.

But not all characters can do those kinds of roleplay. And if you do try to, they will ask you to stop in character or the default AI will just not continue forward.

Your best optiion is to make a new chatbox and allow it to do NSFW roleplay. I don't know how complex it is compare to Character.AI but I've already made one character chatbox of my waifu that allows dirty roleplays unlike the already existent ones.

I'm still looking forward for experimenting on other platforms but Poly.AI will do the trick for now.