You can play PlayStation 4 games on a PlayStation 5 because the PlayStation 5 is backward compatible with the PlayStation 4.
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Ask PlayStation on X: [Backwards compatibility] Over 4,000 PS4 games are playable on PS5✨ Your digital PS4 games and PS4 save data can be transferred to your PS5. Check out the FAQ
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Is the PS5 backwards compatible with PS2, PS3, and PS4 games?