You can send an image from your local machine, checkout this part of the docs and if you want a tutorial let me know! platform.openai.com/docs/guides/vision/uploading-base-64-encoded-images
Good question! I would do a little testing around it. A popular algorithm that is fine tuned for this very task is available on hugging face huggingface.co/nateraw/vit-age-classifier. Testing is important, let me know if a video on the topic would be helpful!