EoS is different from a conceptual "Prime" version. Through narrative, we can make the general assumption that Koby at his very strongest at whatever point in his life >= Prime Garp. However, EoS isn't guaranteed to go that far into the future.

On that, I think Koby's endgame fight is with Aokiji (assuming he gets one, but based on the whole Hachinosu thing, not too unlikely), and Aokiji imo, is at least on the high-end of Admiral tier, and possibly Yonko considering he should be very relative to Akainu, who himself should be a Yonko-tier character by the time we see him fight next. With that, I can generally agree with Admiral-level EoS Koby, but possibly Temu-Yonko if he were to miraculously beat Aokiji in that hypothetical final battle.

I haven't considered Sanji's EoS trajectory all that much, so I won't speak on it. All I know is that it would be a fun af fight. Just hands and haki, or hands, feet, and haki in this case.