@YM185 Thank you for reaching out.
Thank you for exploring Azure Cosmos DB, you cannot change an existing Azure Cosmos DB account to a serverless account directly. However, you can create a new serverless account and migrate your data over.You can create a new Azure Cosmos DB account with serverless and migrate your data to the new account.
See this documentation. https://video2.skills-academy.com/en-us/azure/cosmos-db/how-to-migrate-desktop-tool?tabs=azure-cli
more info: How to choose between standard (manual) and autoscale provisioned throughput
Please let me know if you have additional questions.
Regards,
Oury