You can use the ui-action button element to navigate users to a specific IM or room upon clicking on the button. Refer to documentation for details.
https://docs.developers.symphony.com/building-bots-on-symphony/messages/overview-of-messageml/ui-action-for-your-bots-ui-extensibility/openchat

If what you're asking for is forcefully navigating the user to a chat when a bot sends a message, that is not possible. You can imagine how that will play out if a large number of bots keep doing that repeatedly. The best practice for getting a person's attention is to @mention them so they know it's important, but do this only when necessary, else people will start ignoring your bot's @mentions.
https://docs.developers.symphony.com/building-bots-on-symphony/messages/overview-of-messageml/messageml-basic-format-tags/shorthand-tags#tags