The Gemara in Sanhedrin 22b states:
(Source from Sefaria.org)
:שאלו את רבי איזהו תספורת של כ"ג אמר להן צאו וראו מתספורת של בן אלעשה
They asked Rebbe "What is the haircut of the Kohen Gadol?" He said to them "Go and see the haircut of Ben Elasha"
Is there any visual examples available of what this looked like?