No, this sound bar does not fit this monitor model. The Dell slim sound bar home page has a list of monitors that will fit. The model G3223Q is not included in the list.

Hello - there has been a mix-up somewhere. I did indeed buy a Dell Slim Soundbar SB 521 A. It fits perfectly with my Dell monitor U2421E.
But it fits perfectly on my Dell U2421E monitor.
So not a Dell G3223Q monitor.
Everything clear?
Greetings Hansruedi