No, it is not possible to transfer Pokemon to a game from a previous generation. This applies even if the Pokemon was originally transferred from a game belonging to a previous generation. However, Pokemon may be transported to and from Pokemon Home and Pokemon Bank depending on your game.
Refer to the flowchart below to see where your Pokemon can go. (Please credit me if you re-use this!)
The only exception, as sumwun mentioned before me, is that transferring Pokemon from Gen 2 to Gen 1 is possible if the Pokemon was present in Gen 1.