Hi
Functions that are available via the Messages app on your Apple Watch when it is away from your iPhone depend on various factors including:
- Your Apple Watch model - Series 3 (GPS) vs Series 3 (GPS + Cellular):
- The features of your carrier service plan:
- The type of connectivity that is available to your Apple Watch at the time:
About Bluetooth, Wi-Fi, and cellular on your Apple Watch - Apple Support
Features and requirements that apply under various circumstances are detailed here, including within footnote 1:
How to use your Apple Watch without your iPhone nearby - Apple Support
For assistance with the features of any third-party apps, I suggest that you consult the developers' app descriptions and support resources and, if necessary, contact the developers.