Taking Relief

Dropping a Ball in a Defined Relief Area

New dropping procedure: You must drop the ball from knee height.
Defined relief area: The ball needs to be dropped in and played from a single required relief area (whereas today, although you are required to drop a ball in one area, it can roll outside that area and the Rules may require it to be played from outside the area).
Longest club is used to measure the relief area: You use the longest club in your bag, other than a putter, to measure the relief area.

Reduced time for ball search: A ball is lost if not found in three minutes (rather than the current five minutes) after you begin searching for it.

Relief for embedded ball in the general area: You may take relief if your ball is embedded anywhere (except in sand) in the general area (which is the new term for “through the green”), except where a Local Rule restricts relief to the fairway or similar areas (this reverses the default position in the current Rules).

Substituting another ball: You may continue to use the original ball or another ball, whenever you take either free relief or penalty relief under a Rule.
https://www.rules.golf/en/dropping-a-ball-in-a-defined-relief-area