Hello Yogesh Khatana,
thank you for posting on the Microsoft Community Forums.
Unfortunately, it is not possible to convert a Windows Server 2019 Datacenter Evaluation version to a Windows Server 2019 Standard version using a key of server 2022 standard version without formatting or reinstalling. The only way to change the edition of Windows Server is to perform a clean installation.
Additionally, a product key for Windows Server 2022 Standard edition cannot be used to activate Windows Server 2019. Each version of Windows Server requires its own unique product key for activation.
Hope it helps.
Best regards,
Lei