Spider-Man: Miles Morales can be considered chronologically as a continuation of the first part, because the main character is already Miles Morales, but there is no confirmation from the developer that this is the sequel to the previous game.
But the head of the PlayStation business development in Europe, Simon Rutter, said that “This game is an extension, an improvement on the previous game.” According to him, the Insomniac Games team markedly updated its engine using PlayStation 5 technology.

Some media convey as if this game will be remastered with additional content,
Unfortunately, there are no details about this superhero action. It is only known that the main characters of the game and the new Spider-Man are Miles Morales, and not Peter Parker.
The game release date is still unknown, but may be available at the beginning of the sale of the Sony PlayStation 5 console.