Hi Bryan, what DAW are you using?
Sends and Returns are usually post-effects (after the effects) and pre-fader.
What producers do in this case you're trying to achieve is route the Send to it's own mix channel or mix bus and EQ it separately there. Again, depending which DAW you are using matters for 'how' you are able to do that.
If you use a send on a vocal and have EQed that (an Insert Effect), then when you send it to a new channel and EQ it there, you have EQed it twice (same for any effect of course) and that's ok. Nothing wrong with that, just understand what you're doing. Light EQ and light compression can be applied before it gets sent, then you can EQ the sent effect in its own mix channel there separately (or pan or whatever). If you return it back to the original channel, then you'd have level control (Send and Return levels) and mix it as a combined source. I hope you were able to follow that. There's lots of possibilities within each DAW for this. I probably went into more detail than you wanted.
Sends and Returns are usually post-effects (after the effects) and pre-fader.