How to pitch shift Spotify from en iPhone OSX

Hello!

In parallel to being an audio engineer, I'm a musician and discovered my singing "own voice" late in life. My register is Bass.

Im enjoying singing along with Spotify but it is really hard to sing in pitch with the singer and octaving is not always an option.

I wonder if there is an easy way to pitch shift from the iPhone songs from Spotify to Youtube. Or maybe other streaming services?

Thanks!