Applying the agenda of Time Travel to a story doesn’t always have to be sci-fi nor magical orientated. This is not a craved in stone rule.
There existed many writings and legends about Time Traveling predating sci-fi by thousands of years.
The ancients had many stories about Time Travel. I’m aware that people who read sci-fi appreciate the way authors apply their scientific knowledge. Some may even think a lack of scientific details undermine the credibility of the story. If the science route is the direction the story is based upon, yes, scientific facts and imaginative creations need to be included but if not then adding them will make the story weird.
There’s another route of apply time travel to the story is coming. It’s called metaphysical. Then there’s no way the absence of wormhole, quantum leaps and other scientific explanations undermine the story.
One concept is new. I haven’t read any ancient accounts speaking of traveling to the future. They didn’t believe one could travel into the future. Many believed certain people like seers, prophet, and oracles could see the future but not travel to it.
No, this is not considered magic. It considered a divine ability.
It’s the belief of time is divided by dimensions and other realms exist and there are some people with the ability to travel through them.
When writing about an ability of a character try and make yours unique. Research and learn what has been written about before that’s most likely forgotten. Reinvent it and introduce it to the world. 🙂