"Unusual surnames that have 4 or 5 Chinese characters."
"Rare surnames that have 4 or 5 kanji."
"rare" 「珍しい」
"surnames" 「苗字」"family name" も言えます。
"that have 4 or 5 kanji" 「漢字四文字や五文字の」
"kanji" 「漢字」
"Unusual surnames that have 4 or 5 Chinese characters."
"unusual" 「珍しい」
"chinese characters" 「漢字」"kanji"の方が適切です。
[苗字](https://eikaiwa.dmm.com/uknow/questions/59686/)についてもっと詳しく知りたい方はクリックしてください。
Most Japanese people have two or three Kanji characters in their last name, but once a while you see someone with four or five characters.
この場合、次のような言い方ができますよ。
ーMost Japanese people have two or three Kanji characters in their last name, but once a while you see someone with four or five characters.
「たいていの日本人は、苗字が漢字2文字が3文字だけど、たまに(漢字)4文字か5文字の人を見かける」
to have two or three Kanji characters in their last name で「苗字が漢字2文字または3文字である」
ご参考まで!