Txindex=1: how to recognise the blockchain with this option?

This might be a dumb question: I started the Bitcoin daemon for an initial blockchain download. It immediately started downloading, I edited the Bitcoin.conf file with txindex=1. Stopped and restarted the daemon. How can I be sure the blockchain has txindex=1 correctly set? Should I reminded with the command line Bitcoind -reindex

How can I understand “looking” at a blockchain (day I downloaded from a torrent) that has txindex=1? Thanks