Apps and app updates over 150 MB will require users to connect to Wi-Fi for content to be downloaded.
It's been awhile since Apple last updated the cellular download limit. The last increase was introduced in 2013, increasing the 50 MB limit to 100 MB.
Apple has limits in place to avoid causing customers to unwittingly use high amounts of data when downloading apps, but the introduction of unlimited plans from all of the major carriers in the United States has likely alleviated some of those concerns.
Developers often aim to keep their app sizes under the cellular limit whenever possible to prevent customers from having to hassle with connecting to Wi-Fi to download an app or app update.