If, say, he went .500 this year with that deeply talented and well-developed team, I could see the AD for tOSU telling him "improve dramatically next year or be fired," but the odds of that happening are slim to none. Again, there's simply far too much well-coached talent, and I strongly doubt that Brian Hartline will deviate from last year's offensive plan, seeing how he was the passing game coordinator last year.
Day is a very good coach, and even if he lost to ND and Michigan in the same year, I don't see his losing any other games on that schedule aside from possibly Penn State. At the very most, I could see 2023's tOSU team with 3 losses, but that's not going to be enough for Day to get the ultimatum.
Looking back at history, I suspect that had John Cooper not had that 6-6 season in his next to the last season at tOSU, he would probably have been retained for a while longer.