When you’re writing a new song you’ll often start out wit…

https://www.musical-u.com/learn/how-to-develop-your-new-songs-theme/
When you’re writing a new song you’ll often start out with the seed of an idea. This could be a melody, it could be a chord progression, it could even be an overall idea of the sound of the song.

How can this seed be developed into a full theme?

https://www.musical-u.com/learn/how-to-develop-your-new-songs-theme/