Phone --> EQ --> SPKRS. As long as Phone and SB both have analog connectors, just need the proper cables that's all.
If your phone is talking to the SB wirelessly, no way, because the signal goes directly to SB and never "gets out" for you to EQ it. There maybe an EQ app for your phone, have you looked?
Pshhh.... Soundbars, in general, not made for music.