If you stayed at UT and didn’t make the cut for engineering, you could transfer to other UT schools as long as your GPA is over 3.0. I don’t know what the transfer GPA for A&M is - again, the higher the better. If you really want to be an engineer, you can get a good education at other schools - UTD, UTA, TTU, UH, A&M. They all have good engineering programs.
As far as working less hard at other 4 year schools, I don’t believe that is true. I have a daughter at UTD who was top 1%, NMF and she is working very hard in her major classes (CS). The GE classes were easy for her but her major classes are difficult. So, I guess what I am saying that at any of these universities you will be working hard to get that high GPA.
One thing to consider about UT vs going elsewhere is how many hours are you going in with. If you are going in with 30 AP hours, you really do not have many GE hours left and would need to start on your major’s hours. If you do not have those AP hours, you could go to UT and get them done the first year and see how your GPA is and then make the decision about what to do.
I will say that I think you can be successful with a degree from any of these schools. That is one of the reasons that my daughter is at UTD and not UT. You need to think about which school you could be most successful at. The key is to get the degree from an accredited university, have internships/research and keep a high GPA. Whichever school gives you the most support to achieve those goals is the one you should go to.