I can't find the proper specifications on that Boss audio unit, but one answer said 6w x2 speakers which isn't a lot.
If you can spare 10 more bucks, I have this speaker and it gets plenty loud with good audio quality for blue tooth audio. We only use it at 1/3 of its volume at most on our back patio. https://www.amazon.com/dp/B071H8MJ99/ref=cm_sw_r_cp_apa_fabc_QQD2QAHF7PN6D4J9TWKP