If you do not get into your first choice major, you will not be admitted to Tech. The change was made a year or two again to stop the whole “undecided, but I just want to get into engineering later” thing.
You could go through university studies, but in my opinion, you’d have a better shot of getting in through a science-related, non-engineering degree that has a smaller program at Tech, like Chem or Bio, and then transferring in later. They have been trying to stop people who aren’t actually undecided from entering the COE and if you have any engineering classes, that’s a pretty big tell that you are not that undecided. They did, however, create the Explore Tech major recently that is kind of like engineering undecided. In terms of classes, you would be able to take all the required freshman classes except the first semester engineering course. However, you can take this at the nearby community college, you’d just have to pay for it on your own though. You’d still be on track to declare with all the other engineering major if you did this. Let me know if this helps.