If you search for "Poppy Playtime Chapter 4 free" on itch.io, you will encounter various community-made projects. These are not official but offer a way to engage with the lore for free:
While Mob Entertainment has a profile on itch.io, the fourth chapter is not available as a free download there. itchio poppy playtime chapter 4 free
The official Chapter 4 continues the dark saga of the factory. Poppy Playtime Wiki If you search for "Poppy Playtime Chapter 4 free" on itch
Many independent creators use assets to build their own visions of Chapter 4. For instance, Pizx released a Poppy Playtime Chapter 4 fan game as a small project using a starter kit. itchio poppy playtime chapter 4 free
Some developers like FGSTUDIO have uploaded Poppy Playtime Chapter 4 Demos for Windows and Android.