Unfortunately, there is no simple answer here.
If you have light-weight query profiling enabled, you can use sys.dm_exec_query_statistics_xml to get an execution plan with actual values so far. This can give you some idea of the progress. But it takes quite some experience to make those interpretation from the information. I have rarely tried this myself.
And you may find that all operators up to that Sort operator in the middle of the plan has complete, but non of the operators to the left. How long that Sorting will take - that's not easy to say.
Light-weight query profiling is enabled by default. On SQL 2016 and SQL 2017, you need to enable TF7412.
A second option is to use a Live Query Plan, which will give you more or less the same information, but you can see the numbers being updated. There is also tooling for this in SSMS. I have written about it in this section: https://www.sommarskog.se/query-plan-mysteries.html#livequeryplan.