Depending on the plan your domain is subscribed to, Cloudflare limits data uploads to the following sizes:
The upload limits apply only if you have Cloudflare enabled (Orange cloud next to the DNS records on the DNS settings page). For example, if your domain is subscribed to the Pro plan, a visitor to your website can upload data up to 100MB, per request. This limit overrides any upload limit you may have set over a 100MB at your origin.
If you require to upload resources larger than these limits, you would need to do so through a grey-clouded DNS record so that the Cloudflare proxy is bypassed.