Download the group chat history like so. Do not use the history including media, this will not work.
Follow the steps to produce new messages.
This tool was made before/during the Facebook/Meta takeover of WhatsApp. I am not actively maintaining it and I do not expect their message log formats to remain the same, or even available, indefinetely.
Install the requirements:
pip3 install -r requirements.txt
Run the program (go.py) giving your WhatsApp history:
python3 go.py <your-chat-history>.txt
For further help use the argparse hints:
python3 go.py -h