When you view a player's profile and open their player card, there will be an "Add" button below. You can tap on this button to send them a friend request.

You can also send a friend request to suggested players by following the steps below:

Navigate to the "Leaderboard" section,

Go to the "Friends" tab,

Tap on the "Add" button.

There will be players on this list who are your teammates or who have mutual friends with you. You can either send them a friend request or dismiss the suggestions.

If you scroll down to the "Find Friends" button and tap on it, type in your friend's User ID to add them. You can also tap on the "Invite Friends" button to share your friend request URL or invite friends within the Messenger.

When your friends tap on the link, they will become your friends in Truck Star.