From type/Uni

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method codes(Uni:D: --> Int:D)

Returns the number of codepoints in the invocant.

From type/Cool

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sub codes(Str(Cool))
method codes()

Coerces the invocant (or in sub form, its argument) to Str, and returns the number of Unicode code point.

say 'møp'.codes;    # OUTPUT: «3␤»

The same result will be obtained with

say +'møp'.ords;    # OUTPUT: «3␤»

ords first obtains the actual codepoints, so there might be a difference in speed.