We just trim the straggly bits. Prevents tangling and gets rid of split ends which means less detangling.
Shaved it short at 18 months. We never let it grow out too long til he was old enough to understand he had to sit longer than most to have it done as its insanely thick 4b/c hair
We cut our sons hair right before his 2nd birthday! You can definitely trim it especially if it’s getting in his way or it’s hard to care for. 100% your choice