I’m pretty sure that there isn’t much difference between 2.9 and 4.2 as far as UV unwrapping goes. I’m curious as to which part you can’t do? In 4.3 they rearranged the menus and made changes to how the smart UV works, but most of it is still the same. You just have to do a little hunting to find the options. There were additional options added to UV Project in 3.6 and support for non-square images.
