Ubisoft is really trying to get you to play Skull and Bones.
The demo/trial is available where the game is available - PlayStation 5, Xbox X|S, Epic Games Store, and the Ubisoft Store.
The free trial gives you unrestricted access to the game's features and modes for 8 hours. All your progress will carry over should you decide to purchase the full game.
If you look at reviews, you might find the game to be lacking, sitting at 64 on Metacritic and 60 on Opencritic, but review scores are one thing, your own personal enjoyment is another. Who knows, it might be exactly what you're looking for. You won't know until you try it yourself.