Link/deeplink to a new chat with default message

LiubovMurarova 
See : 
Create deep links to content - Teams | Microsoft Docs
Use this format for a deep link that you can use in a bot, connector, or messaging extension card:

https://teams.microsoft.com/l/chat/0/0?users=<user1>,<user2>,...&topicName=<chat name>&message=<precanned text>

The query parameters are:

• users: The comma-separated list of user IDs representing the participants of the chat. The user that performs the action is always included as a participant. Currently, the User ID field supports the Azure AD UserPrincipalName, typically an email address only.
• topicName: An optional field for chat's display name, in the case of a chat with 3 or more users. If this field is not specified, the chat's display name is based on the names of the participants.
• message: An optional field for the message text that you want to insert into the current user's compose box while the chat is in a draft state.

Note : this currently (march-21) works for :
- users in the same tenant ,

- and x-tenant users that have been in chat contact before