Yes and no. You are subject to the policies of the carrier where the bags are initially checked. So if you are flying as a non-status passenger in CO's BF to PSA routing EWR-(CO)-CDG-(AF)-PSA where the last segment is in Y and is a CO codeshare operated by AF (I do not know that such exists, but go with it for the sake of the example) then you are still allowed 3x 70 pound bags all the way to PSA, even though the AF policies would allow much less. On the return, however, you are subject to the AF Y limitations at check-in.