Cambridge English defines the 2nd conditional as:
Imagined conditions: the second conditional
We use the second conditional to talk about the possible result of an imagined situation in the present or future. We say what the conditions must be for the present or future situation to be different. We use a past form in the conditional clause to indicate a distance from reality, rather than indicating past time. We often use past forms in this way in English.
If you can read and understand that and build a sentence from that, congratulations. I cannot. Like all my grammar, I teach using real world uses instead of memorizing grammar rules. For this construction, we unlock our imaginations. I setup the sentence and let my student finish it off. They might need help with some words. We write each thing down and repeat.
… on a spaceship.
… playing with my friends.
… on an island.
If I weren’t me, I would be …
… a space captain.
… a famous basketball player.
… a pirate.
If I lived in a different time, I would live …
… in the middle ages and be a knight.
… in the future and drive a flying car.
… in America and be a cowboy.
If I was rich, I would buy …
… a collection of cars.
… every LEGO set, ever.
… a giant swimming pool.