Google has now moved its “Change of Address” tool to search console interface, as Google has totally moved from webmaster to new search console few months ago .
Previously it was available in the old version of webmaster and not moved at the time of transaction from webmaster to search console.
This is very important tool for the site owners as it’s a path conveyor to google if a website is moving from old domain name to new domain or sub-domains.
Its helps google to understand that the previous domain is permanently moved to new domain, so that google doesn’t make any change to its ranking.
Please make sure while using tool as this should only be used if you are migrating from old domain to new domain permanently.
This tool should not be used if you are redirecting HTTP to HTTPS or changing urls within the same domain.
The Change of Address tool is only a part of domain change procedure and not for any internal urls for a specific domain.
This should be done through 301 redirects, altogether this tool is smart enough to help you out migrating from old domain to new domain, and after successful completion of the task, it will tell Google about the address change.