Conditional access policy without Client Apps condition

[Gurdev Singh]

Is it required to configure 'Client apps' condition in a policy?

When 'client app' condition isn't configured, it says 'policy applies to browser and modern auth apps'. 

I note that this condition is still in 'preview'. Would anyone know the impact of changing a policy enforcing MFA that has 'client app' condition not configured to a policy that configures this and includes all the client apps i.e. Browser, Modern Auth Client and Other clients.

[#2]

It's explained in the documentation: https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/conditions#client-apps