Yes, in 'echo 3 true story', 'echo 3' is likely related to the 'true story'. It could be the name or identifier for the events that make up the true story.
Most probably. Since it's presented as 'echo 3 true story', it implies that 'echo 3' is an integral part of the 'true story'. It might be a key element, such as a project name, a character's code name, or the name of a place that is central to the events of the true story. For instance, if it's about a military operation, 'echo 3' could be the operation's name and the 'true story' would be about what actually happened during that operation.
Sure. In the phrase 'echo 3 true story', 'echo 3' is surely related to the 'true story'. 'echo 3' might be the main subject or the starting point of the 'true story'. For example, if the 'true story' is about a scientific discovery, 'echo 3' could be the name of the experiment or the research group involved. It's the connection that ties the story together and gives it a specific focus within the context of a true account.