In my experience the best bonding experience for siblings is Escape Rooms. This is especially true for siblings that may not already be very close, or have a large age difference.
There is something unique that happens when people are locked in a room together and are forced to collaborate to escape. In the excitement, people tend to band together and work as a unit. This means lots of communication, problem solving, and a shared goal. Better yet, after the experience there are usually hours worth of conversation to be had discussing likes/dislikes, the exciting bits, or how it could have been better. The uniqueness and adrenaline rush of the experience makes it second to none for sibling activity in my book.
Contributor: Brendan Dubbels, Co-Founder at escapebase