Hi Jeevan,
You must already have a paid license of Dynamics 365 Customer Service Enterprise in your tenant that was purchased directly through the Microsoft 365 admin center (that is, Web Direct), otherwise the Chat and Digital Messaging options won't be visible.
and then you can start a 30-day trial of Chat or Digital Messaging with 25 user licenses.
After signing up for a trial, you must assign licenses of Chat or Digital Messaging to the users who need to engage with customers and provide support via Omnichannel for Customer Service. This can be done by selecting one or more active users and editing their product licenses.
Please have a look at this :
docs.microsoft.com/.../try-channels
Please see this MS Ignite session for details and demo.
www.youtube.com/watch