Phoenix sits next to 3 phonetic neighbors — Felix, Phineas, and Lennox are the closest matches by sound. Most share Phoenix's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"dark red, crimson"
"man from Lucania"
"lover of hounds, wolf lover"
"flowing body of water"
"modern American invention"
"lion"
"tumult, noise"
"victory of the people (short for Nicholas)"
"son of David"
"young seal, seal-born"
"descendant of the red-haired one"
"crowned with laurel"
"adornment, goodness"
"God is gracious (via John/Zane)"
"son of Owen"
"young dog, whelp"
"master, conqueror"
"at the ash tree"
"conqueror, winner"
Similar sound: These names share phonetic patterns with Phoenix — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Phoenix.
Rhythm: Phoenix is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.