Every official source — both trailers, the Rockstar Newswire posts, and the PlayStation and Xbox store listings — names PlayStation 5 and Xbox Series X|S and nothing else. There is no asterisk and no "more platforms to come" language.
This is a different situation from the PC question. With PC, Rockstar has simply stayed silent, and its own history makes a later port likely. With PS4 and Xbox One, the hardware is two generations behind what the game targets.
GTA V shipped on PS3 and Xbox 360 in 2013 and was later rebuilt for newer hardware, which is why some players expect the same pattern in reverse. That is not how this release works.
Leonida is roughly twice the size of GTA V’s map with far denser detail, more interiors, a rebuilt weather system, and over 170 animal species running simultaneously. The mechanical hard drives and memory budgets in PS4 and Xbox One cannot stream a world built to those specifications.
Playing GTA VI means owning a PlayStation 5, PlayStation 5 Pro, Xbox Series S, or Xbox Series X. The Series S is the cheapest route onto current-generation hardware, though it targets lower resolutions than the Series X.
If you would rather wait for PC, treat that as an unconfirmed possibility rather than a plan — Rockstar has announced nothing, and its past PC ports arrived between eight and seventeen months after the console release.