Migration – Trapped in the iPhone 4 and WhatsApp, need help to escape

I have an iPhone 4 with WhatsApp Messenger installed. The iPhone is no longer updated, works very slowly and has no more space available. In addition, WhatsApp is no longer updated, because the most recent versions of WhatsApp require a newer version of iOS, which in turn requires me to get a new iPhone.

My WhatsApp conversations contain information that I can not afford to lose. That's why I can not just drop this iPhone.

Recent versions of WhatsApp allow synchronization of the conversation history via iCloud, but my version is too old and lacks this feature.

I was able to save photo and video files from WhatsApp conversations on an iPhone, then download them to a PC via a USB cable, but I can not do it anymore because the iPhone has more free space and I can not release it (that is the subject of another question.). In addition, this approach does not work for text messages.

The situation is getting worse by the day, because as long as I can not migrate WhatsApp to another smartphone, I continue to receive important information about this iPhone, where it gets trapped.

Any help would be appreciated.