Hi @Gurdeep Singh
It is not wise to migrate into .NET Standard 2.0 as it is already announced that there won't be any new version after .NET Standard 2.1 but only .NET 5+. .NET 5+ replaces the .NET Standard.
There will be no new .NET Standard versions after 2.1. For more information, see .NET 5+ and .NET Standard .
Please check the future of .NET standard
https://devblogs.microsoft.com/dotnet/the-future-of-net-standard/.
Since, you are migrating better to go for latest version .NET 6.
However, if it is your requirement, then you can migrate to .NET 6 with the Upgrade Assistant. Then, downgrade to .NET Standard 2.0 from the project properties.