Sorry, but the desktop app doesn't have an equalizer.
The idea of having a desktop equalizer is here:
It is currently marked as "Watch This Space", so there may be future updates on this. You can add a kudo and a comment to help support the idea.
Also, if you cannot wait for this feature, there is an unnoficial addon called Equalify. It adds a 10 band equalizer to spotify. You can find it here:
you are using windows correct? if so go down to the speaker icon at the bottom on your taskbar. click on it then press mixer. fom there click on the icon for the speaker you are using then a new window should open that says speaker properties and should have 4 tabs(general,levels,enchancements and advanced) click the enchancements tab. put a checkmark on equalizer. go down where it says settings and you can pick from the default (pop, rock, bass boost, vocal, etc.)or tou can create your own setting with the (...) button. hope this helped.
This is a million times better than using an EQ within Chrome. For those who aren't familiar with Equalizer APO, it is probably the only free way to easily apply EQ changes system-wide on Windows (I've looked a lot).
You could use the built-in Configuration Editor as well but it's much more clunky (and non-resizable - it's tiny!) After installing Equalizer APO, restart your computer. Then drag the Peace application into Program Files>EqualizerAPO>config. Then run Peace and you'll have your EQ.