@Thao Nguyen1 @Joshua Chen MTL I might have been incorrect, taking a second look. Thanks Joshua for that link you provided 

according to the Yokohama/Vancouver Field Service Management documentation, Knowledge Base (KB) articles that are attached to a Work Order Task (WOT) in the Now Mobile Agent are accessible in both online and offline modes servicenow.com+8servicenow.com+8servicenow.com+8.

Specifically:

• If a KB article has been attached to a WOT, it is downloaded and cached locally when the technician syncs or starts offline mode.

• The article can then be viewed even without network connection, which helps in field scenarios with no internet access.

Lets try this 

1. Make sure the KB article is attached to the Work Order Task record.

2. Enable and configure offline caching in the Field Service Mobile app (e.g., Request Offline, relevant plugins).

3. Have the technician sync or start the offline session before losing connectivity.