The PlayStation 5 will offer backwards compatibility, and now Sony’s patent with the United States Patent and Trademark Office explains how it will work.
Besides the backwards compatibility, it was shown that current gen games will run noticeably better on the PlayStation 5. A good chunk of that comes from the fact that the PlayStation 5 has an SSD under the hood, but the May 28 patent shows exactly how they will run on the next-gen console.
The patent abstract:
“Performance of a new system may be optimized to run a legacy application written for a legacy system. Performance information for the legacy application is recorded or derived while running the legacy application on the new system. Performance characteristics for the legacy application running on the new system are determined by analyzing the performance information. The performance characteristics include one or more key performance metrics and other performance information. The key performance metrics must be met when the legacy application is run on the new system. The other performance information is useful for adjusting one or more operating parameters of the new system when running the legacy application on the new system. The one or more operating parameters are adjusted so that the one or more key performance metrics are met.”
Instead of changing the game's code, the PlayStation 5 can adapt itself to emulate the PlayStation 4. This would allow developers to fine-tune their games to run as best as they can on the PlayStation 5, even though they weren’t developed for it.
It’s a rather long document and it’s not easily understandable, I didn't understand it fully, so it’s probably best to read it for yourself if you’re really interested in how exactly it will work.