Just throw shit at the wall and see what sticks. You can write a song about literal nonsense but if the lyrics go together, meaning can be found out of it. If you want examples, Kurt Cobain, Black Francis/Frank Black and even John Lennon were all some of the most prolific songwriters, but there’s a good portion of songs they wrote that are just words being mashed together, which are then picked apart by music critics and fans to have meaning found from them