Spotify streams are handled by Spotify's own app and can't be routed through a browser tool directly — but the same EQ thinking still applies.
Load a local copy of a song here to experiment and find a curve you like, then recreate that shape using Spotify's built-in equalizer in the app's Settings menu. Understanding what each of the four ranges does makes Spotify's own EQ screen much less confusing to use.
Spotify's mobile EQ shows more bands than this tool does, but the same logic applies: whatever adjustment you found worked at 60Hz here should map to Spotify's lowest slider or two, and so on up through its higher-frequency sliders.