Hi,
Thanks for reaching out to us. There is not that kind of online tool that you can upload your SSML file and then get the audio file directly. The most similar one is the REST API. After you set up everything about your service(mostly authentication), you can use it as input the SSML file to the REST API and then get the response.
Please take a look, https://video2.skills-academy.com/en-us/azure/cognitive-services/speech-service/rest-text-to-speech
Thanks,
Yutong