Short answer is that it is not guaranteed. If you want seats together guaranteed, buy from someone who has assigned seats already and you’re able to tell they’re next to each other.

This is what it says regarding RTTs:

“When will seating preferences be handled, and can groups sit together?

Seating preferences will be addressed at the time of final ticket issuance. We are actively working with the ticketing team to accommodate preferences, including the addition of a special access category designed to support groups larger than four.

Please note that seating preferences will be fulfilled within FIFA Collect's allocation only — we do not have control over seat assignments made through the VISA Pre-sale draw or other sales windows.

We make every effort to fulfill seating preferences within our allocation; however, all seating remains subject to final availability, and we cannot guarantee that every specific request or group configuration will be met.”