You can collect text files using the MMA or AMA agent. If you don't see any logs it could be a configuration issue...wrong location or invalid parsing. Also, I believe this relies on the file timestamp. The file must be updated regularly.
https://learn.microsoft.com/en-us/azure/azure-monitor/agents/data-sources-custom-logs
https://learn.microsoft.com/en-us/azure/azure-monitor/agents/data-collection-text-log