In the old days it was radio, genre specific late evening shows were good for hearing new stuff.
Swapping CDs to listen to in class was another good one, or the old one earbud each - I had a mate who used to bring this massive folio of cds to school and had plenty of exposure to music from older siblings that I hadn’t heard.
I also remember trawling through the local metal record shop’s online catalogue and then spending a laborious few hours downloading an mp3 of any bands whose name appealed to me.
But yeah, these days basically spotify from the playlist that follows an album I’ve put on. Also tv shows and occasionally podcasts.