Your first sentence, "Is this a new feature in Opay? How true is it?" is grammatically correct, but it's slightly unconventional to use "in" when referring to software or applications. "On" is typically more appropriate in this context.
The second sentence, "Is this a new feature on Opay? How true is it?" is grammatically correct and more common.
**Meaning**:
- The speaker is inquiring whether a specific feature is newly available in the Opay