To chat with with a friend without internet, make sure that:
Condition 1: Your friend is within 100 meters of you. Of course the closer you are, the better the connection.
Condition 2: To start a connection, also ask your friend to tap on hike direct option from your chat.
Step 1: Tap 3 dot menu > hike direct
Step 2: Connecting to contact
Step 3: Accept at recipient's phone
Step 4: Tada! Share messages, files as usual without internet.