Sonny sits next to 4 phonetic neighbors — Sunny, Benny, and Ronny are the closest matches by sound. Most share Sonny's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son, young boy"
"son of the king"
"son of Nicholas (via Cole)"
"from the Stetson hat-making family"
"fair, white, bright"
"to tame, to subdue"
"the third (son)"
"valley settlement"
"son, born of"
"excellent; unbeatable"
"animal enclosure, warren"
"son of Hendrik"
"handsome at birth"
"manly, brave"
"altar/hearth of God"
"shelter, dwelling"
"strong lord, powerful chief"
"upright, fair"
"strength, dominance"
"little fawn"
Similar sound: These names share phonetic patterns with Sonny — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have English origins, giving them the same cultural heritage as Sonny.
Rhythm: Sonny is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.