here's the thing, songs aren't typically meant to be in stories. they're usually pretty cringey when they're added. coming from personal experience. so, to save you the future embarrassment, i'm gonna give it to you straight:
do not insert a character singing a song into your book.
there's very few times where people can just make it work. i've only done so once, and i think i've tired three... may four?— times. and that was because it was a crack fic, and the songs fit into the chapter just right. and nothing about it was serious. and i still don't really even like it.
anyways!
i think the only time it can be successfully executed is if it's a text fic and they're... well, texting. and it's like a funny line from a song that's just like a good response or something. idk.
even though i have limited knowledge about this topic, i can promise you one thing; no one wants to see your character singing fight song in front of a crowd.
i can't really tell you what to do though. in the end, you do as you please. i just wouldn't recommend adding songs into your writing unless it's like absolutely needed or it's comedy gold. have fun writing though!
oh, and it's fine if you create playlists for your readers to listen to while they read but place that in the intro.
from: your favorite author ;)