Reliably Broken Sort
JavaScript (ES6), 39 34 bytes
a=&gt;[a.sort((x,y)=&gt;x-y).pop(),...a]

Sort the array in ascending order, pop the last element and use it as the first element of a new array. Then destructure the remaining elements of the original array into the new array (In JS, both sort and pop modify the original array).

Test it


o.innerText=(f=

a=&gt;[a.sort((x,y)=&gt;x-y).pop(),...a]

)(i.value=[1,2,3]);oninput=_=&gt;o.innerText=f(i.value.split`,`)
&lt;input id=i&gt;&lt;pre id=o&gt;