whats the equivalent osund in polish to ch as in chess

In Polish, the closest equivalent to English ch as in “chess” is usually cz.

Pronunciation note

Polish cz is pronounced like the ch sound in chess or church , though it can sound a bit harder or stronger than English.

Important distinction

Polish ch is not the same sound as English ch in chess ; in standard Polish, ch and h are pronounced the same way, as a guttural h -like sound.

So the short answer is: English “ch” in chess = Polish “cz”.