Here is a complete article exploring this topic, the technology behind it, and where to find these resources.
In the meantime, here's a for offering a free file (adjust as needed): archivo de free para pegar todo rojo work
Freepik offers thousands of free red-themed PSD files. Search "red banner" or "red social media post" and download layered files. You can copy layers and paste them directly into your own PSD. Here is a complete article exploring this topic,