Asensio is trash atm and his style isn't too dissimilar to Dybala (left footed player who relies heavily on his dominant foot). His best position in theory is as SS/CAM which is pretty much the same spaces Dybala occupies. He's 23 in February too so not like there's much of an age difference. Would be a pointless signing.
Isco, however, would be interesting as he's more versatile and can play CAM/CM (mezzala) and effectively free roam across the entire front-line. The latter is he was doing against us in the final in 2017 and the QFs earlier this year. He was given license to operate across the whole pitch behind Bale & Ronaldo. His assist for Ronaldo's opener came from LW.
Ultimately for Juve though, he'd play the "mezzala" role.