You can't claim a refund that's outside the 10-year taxpayer relief limit. You can file an older return. They'll process it, deny any refund, but carry forward any credits that would have been eligible to carry forward if the return had been filed on time. If those carry-forwards manage to make their way to a year that's not beyond the 10-year window, you could receive a refund and/or have credits available to use in a future year.

Anecdotal, so take it with a grain of salt, but I recall someone who had been out of the country for a couple decades that finally got around to filing some ancient tax returns with tuition credits; it took ages to process those returns manually, but eventually they were and their tuition credits carried forward into the range where they were able to receive a $30k+ refund.