Hello! Nice question. Those are different. Want in (to enter or participate in a situation) and want out (to leave a place or situation ) are PHRASAL verbs. There are no 'want +up / down' variants. In case of up and down, the verb GO is used. So, if you want to go up or down, it is more common to use upstairs and downstairs. Have a great day!

Your English is excellent. The only comment that I would make is that tiredness is not a very common word. The more usual word would be fatigue.

I want out and I want in I'm not the same as saying I want to go in I want to go out. That would be baby talk to use those expressions in that way. If there is an arrangement, an investment or a game for example that you wanted to join, you could say I want in. Conversely if you are in such a game or arrangement and you want to leave or don't want to continue, you would say I want out. You're in Las Vegas and walk up to a blackjack table. You would say I want in. After you have lost all your money you would say I want out or I am out.