Problem statement
Currently have the Classic Universal Login configured on the tenant but would like to test out the New Universal Login experience without cutting all users over immediately.
Solution
Review the differences between New and Classic versions of Universal Login. For more information, refer to New & Classic Login compared. Be aware that there may be some features present in Classic Universal Login that are not yet available in New Universal Login.
In order to become familiar with the features of New Universal Login, it is recommended to setup a Development tenant. This can be configured to closely mirror the current Production tenant, though the key difference is that it would allow all of the desired New Universal Login features to be explored.
Related References