Hi Ankush Bondgulwar,
Mendix studio is like and Beta version but Studio Pro is an Advance module
Check this document about Mendix studio : https://docs.mendix.com/studio/
Mendix studio has no feature like (Event handler)
I hope It helps for you..
In studio pro, you can find event handlers in the entity properties. In the web version, it is not (yet) implemented
In Studio Pro, this is implemented in the entity definition. In a domain model, double-click the entity, go to tab Event handlers and click new.
In the web version, it is not (yet) implemented. This is probably either by design-choice of Mendix, keeping the web-version lightweight and easy to use. Or they simply have not (yet) gotten around to extending the Mendix Studio functions with more complex functions. StudioPro has been around over 15 years. Studio only since 2019 or so.