It depends. Some parts of Franklin might be based on real events or people, but it could also have fictional elements added for entertainment purposes.
I don't think Franklin Murray is part of DC Comics. DC has a vast array of characters, but this name doesn't ring a bell among the popular or established ones.
SP Phoenix was the hero in the game Sword and Expedition and its derivative works. SP Phoenix's real name was Phoenix, also known as Phoenix or Firebird. He was a Mythical Hero from the Glorious Empire. He was an Agility-based Hero that dealt explosive damage. His skills included Phoenix's Nirvana, Ashes Rebirth, Radiant Baptism, Fiery Feathers, and so on.
While waiting for the TV series, you can also click on the link below to read the original work of " Little Fox Demon Matchmaker " to understand the plot in advance!
I'm not sure specifically as there could be many stories named 'Franklin in the Dark'. It might be about a character named Franklin who experiences something in the dark, like an adventure, a discovery or a spooky encounter.