Hope you are doing good! Thank you for reaching out. Please find the answer below.
1.Microsoft 365 Developer Program: This is a great way to get a new test tenant for free. You can join the Microsoft 365 Developer Program and follow the steps to set up a new subscription. This will give you a fresh tenant that can be used for testing purposes.
Developer Program | Microsoft 365 Dev Center
2.Trial or Purchase: If you're not eligible for the Developer Program, you can sign up for a one-month free trial or purchase a Microsoft 365 plan Free Trial - Try Microsoft 365 for a month - Microsoft Store
3.Manual Creation: You can also manually create a new tenant by following the steps Quickstart - Access and create new tenant - Microsoft Entra | Microsoft Learn
Ensure that your Microsoft account is not tied to any old or existing subscriptions that may affect creating a new tenant. If you still encounter issues, double-check that there are no restrictions or any lingering account settings that might be preventing you from creating a new one.
If the issue still persists, we'll happy to assist further needed. "Kindly mark the response as answered if the issue resolved".