Using a speaker connected to the iPhone

I recently bought a speaker called soundcore flare and the way to use it is if it’s connected to the phone and it just plays everything from my iPhone like I basically can’t be on a phone call and just listen to music because then the phone call will play through the speaker or if I’m texting the clicks will play and all that but I wanted to know if there’s a way I can make it to only play sound from a certain App because I have Apple Music too and I know you can do this on the Samsung phones so it’s no reason for it not to be on the iPhone and if I can’t is there a app I can use to stream music on and make it so only sound comes from that app and not just my whole phone because I know other speakers have there own app that lets them do this but they are way to much and there isn’t a reason I can’t on a certain app so please help if I can’t then I will like to know because if I’m just listening to music and texting the clicks from texting will be heard but I can put it on vibrate but the issue is being otp or if I’m on Instagram and want to listen to a video with it playing through my actual phone and staying connected to speaker or if there’s an option to just connect speaker to Apple Music and only play stuff from the app and not whole phone