Zoom In is a specific action option from the Lean Startup toolkit. Strictly speaking, this is a possibility of pivoting, i.e., changing the strategy to achieve the agreed goal.
The Zoom In is one of ten options Eric Ries (author of “The Lean Startup”) suggests for a pivot. The Lean Startup method, which Ries helped develop, is about starting a successful business or product launch with as little capital and reduced processes as possible. Instead of a long conceptualization, the goal is to bring a prototype or beta version to the market as quickly as possible. In addition, the product cycle should be kept as short as possible so that customer feedback can be used to respond quickly to requests or changes.