he can’t change the constitution
No, but he's sure proven that he can ignore it. And the Supreme Court will ultimately back him up. And they've already ruled that he can't be charged with anything illegal he does while president (the courts won't even punish him for crimes he was convicted of when not POTUS). And even if they don't rule in his favor he's shown he's willing to ignore the courts when they don't rule in his favor.
If the cops and military side with him- and there is a good chance the majority in both groups are MAGAts, he'll just have people participating in the 'illegal/illegitimate' elections arrested.
If he's still alive in 2028 he will not give up power, I guarantee it.
I hope you are right.