This XrmToolbox tool provides a smart interface to update the Field Attributes of your Power Apps Entities.
Reactive Fields Updater is thought to update the Fields Attributes for specific Entities in Power Apps. You can easily increase or decrease Attributes such as Max Length on a Text field, or Max and Min Value on Integer fields.
Start by loading your Entities from the Organization you're connected to. Then select an Entity and a Field from that Entity. In the right corner, the Attribute box will display the actual values for the Attributes you can modify. Every change will be listed as a new Operation in the box below. You can check and uncheck the operations that you want to execute, and then just click "UPDATE !". You can also check the operations to be unlisted with the "Clear" button.
Image you got a set of 20 custom Entities and you need to increase every "Name" Max Length from 100 to 800: Reactive Fields Updater is a valid alternative to Power Apps when it comes to multiple or repetitive operations to be performed at once, since multi-entity operations are supported.
This tool can be downloaded from XrmToolbox Tool Library. You can connect to your Organization, then you're ready to go.