Not yet. As of right now, you cannot play Roblox on PS5 or PS4. Roblox is currently not available to purchase or download on Sony's PlayStation consoles. However, the game has been confirmed for release on PS5 and PS4 in October 2023.
This doesn't come as a huge surprise, given the studio was hiring a PlayStation software engineer a while back, and that PlayStation's top dog, Jim Ryan, recently relaxed the company's stance on Roblox coming to PS5 and PS4.
Roblox is available and playable on PC, Mac, iOS, Amazon Fire, Android, and Xbox One. The game is accessible on many devices, and starting in October 2023, PS5 and PS4 will form part of that list.