No they didn't.
Only in nostalgia episodes that were deliberately going for "retro" as part of the appeal. Discovery's pretty firmly nailed that coffin shut with the redesign of the Enterprise.
The Disco-prise is no more set in stone than the original version was (or, if you want to get technical, the Cage, WNMHGB, Series, T&T, IAMD, and both remastered versions were). There's nothing to stop them from showing a more faithful version of the TOS ship at any point in the future. nuBSG replaced, like, half of their ships with different versions over its run. Stargate: Atlantis revamped their Puddle Jumper set every season without a word to suggest it hadn't always looked that way (and never mind that their effects houses all used their own CG models, so the Jumper and the City itself changed appearance drastically from episode-to-episode or even scene to scene). The uniform switch in TNG. The Millennium Falcon between ANH and ESB. The
Enterprise between STID and STB. These things happen all the time.
Hell, if whoever has been pushing for a more retro look behind the scenes and then been overruled at the last minute wins the right fistfight in the next few months, we could sit down next year and watch the "Previously on Discovery" teaser in the very next episode with a more "originalist"
Enterprise swooping into view, complete with the hall markings on it and
Discovery having mysteriously switched from
futuristic Eurostile* to space-age
AmarilloUSAF, probably with some damn light in the scene. And we'll all just pretend it was always like that.
*I know it's really Microgramma, don't @ me.