Penn sits next to 5 phonetic neighbors — Ben, Len, and Ken are the closest matches by sound. Most share Penn's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"hill, headland, enclosure"
"calm, serene"
"heavy club weapon"
"one who throws, thrower"
"fire of Yahweh"
"beauty, grace"
"broad ford, wide river crossing"
"high mountain, exalted"
"dealer, trader"
"bent grass clearing"
"god of thunder and strength"
"given by God, God's gift"
"prince, royal heir"
"smooth, tender"
"strength, power"
"God strengthens, God will strengthen"
"wagon driver, cart maker (from Old English Wayne)"
"young person, noble youth"
"chamber, enclosed space"
"wine's town, friend's settlement"
"from the white settlement"
Similar sound: These names share phonetic patterns with Penn — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Penn.
Rhythm: Penn is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.