Is it possible to get SObjectType dynamically from field token like
No, it is not*. The only method that a field token has is
getDescribe(), and the
DescribeFieldResult class doesn't contain any methods that return which SObject the field is for.
*: Not for all fields, at least. It is likely possible if you are working with a relationship field and use the relationship name. I don't think that approach is practical/useful though. Since you need to hardcode the field token or use an sobject token/describe to get at the field tokens/describes, you should have a better source for that information anyway.