In case you extend an initial role: make a copy from it, then add some additional capabilities, such synchronization would be achieved via multiple roles assignment to a user: initial role, 2nd role with additional capabilities. User will have a full list of capabilities as a result. Any updates applied to an initial role will be applied to such user automatically.
If you start from an initial role in order to narrow its capabilities list, then auto sync of new role with an updated initial role to difficult to realize, as you never know what to change automatically.
WordPress changes default roles very rare. It’s not too difficult to monitor such changes and add/revoke 1-2 capabilities manually after one of WordPress core updates was installed.
I do not see a need in a described functionality according to all of written above.