It’s more CPU than GPU bound, especially at high refresh rates!
As a comparison, I’ve got the same GPU and an i5 9600k (faster SC, slower / less MC) and I get smooth 70-80 FPS in Boralus and raids, I doubt it’s possible to consistently hit a very high framerate there.
However to answer you question, 144 Hz > 60 Hz, so go for it! the 1660 Ti is great for 1080p in general.
if you’re trying to play on a 1440p panel though, I’d recommend the RTX 2060 / 2070.