That would depend on what resolution you game at and the settings you use. But I would suspect that the Ryzen 5 1600 is still able to hold its own against the GTX 1660 Ti. I used to have a GTX 1070 with my 1600X (4GHz) and noticed no bottleneck. But I'm not a competitive gamer.
Then you are like me. The highest settings for the best appearance. You should be fine with the 1660 Ti at ultra settings. CPU bottleneck shouldn't be an issue.