How to check user permissions in linux?

Question

linux

Created a user as root
Assigned sudo rights to him
Logged in as user
1. How can a user find out what rights he has? Or how to make sure you have sudo rights?
2. This user did not appear either in etc/sudoers or in the etc/sudoers.d folder, there were no changes. Where, then, is the list of users with sudo rights stored in the system?

Answer 1

/etc/group sudo group?