Yes, at a high level there are typically two paths to get to an unusually large aid offer from an LAC, neither certain:
(A) Get admitted to one of the very wealthy LACs with really large need aid budgets such that it will give you unusually large aid based on demonstrated need; or
(B) Get a need + merit offer from one of the LACs with less of a need budget but also a substantial merit budget.
A lot of the former are East Coast, and tough admits because a lot of highly qualified people apply for far too few slots, which is one type of uncertainty. Unfortunately, although they are still test optional it is possible that at least for some of them, your odds might be lower going test optional, which heightens the uncertainty.
OK, then a lot of the latter are in the Great Lakes/Midwest plus a few other areas, and typically at least somewhat easier admits than their East Coast academic peers. But then there is the uncertainty of whether or not you will get enough merit aid to combine with their need aid to get them inside your budget. Test optional might up that uncertainty a bit as well, although I am actually not sure it has the same marginal effects in all those cases.
Anyway, my guess is your best strategy will end up involving trying some of both. If your son would prefer one of the wealthy East Coast LACs options, hopefully one will come through. But if your son would at least prefer one of the non-East Coast LAC options to an in-state public, then it will probably be a good idea to apply to some of those as well, in case none of the wealthy East Coast LAC options come through.
Fortunately I think Oberlin is way out there on the artsy/quirky end of things, and a lot of the other LACs I named would potentially be more “middle-road”. This idea may take some getting used to, but I think for a kid interested in history and philosophy, a college like St Olaf, say, could be great. If he liked things like the curriculum plan at Vassar, maybe Kalamazoo, which has something they call the K Plan which is very cool. And so on. There can be things to love about all these LACs once you really dive into them.
Again, he doesn’t have to immediately rank any of those ahead of, say, Bowdoin. But if he would like some of them more than his in-state options, then they are probably worth including on his list with the hope of a big merit offer to get them on budget.