What happens with rain policy? Will they close the theme park?

No, the park will not be closed. Some rides will be shut down - outdoor ones - especially if there is lightning anywhere in the area

We were there on a rainy day. It wasn't a downpour, but still. Nothing closed and everything went on as usual

The outdoor rides will be closed, but all the indoor attractions will stay open. Bring a poncho!

No but some rides might be shut down.

Not usually, most rides are inside, some rides will be closed