So it looks like were not gonna get the series finale, At least not as originally intended. Tons of shows are ending their seasons prematurely since all production has stopped nationwide due to COVID-19 but Supernatural and Empire are hit the hardest, Both of these shows are 1.5-2 episodes shy of filming their final seasons and it doesn't look likely at all that production will start back up before they run out of episodes to air since both shows are back airing their final block of episodes.
At this point the best we can hope for is a "Finale event" where they can film and air the last 2 episodes sometime later this year or early next year. Really sucks man!
Coronavirus-Related Shutdowns Leave Series Without Finales, Create Dilemma For ‘Empire’ & ‘Supernatural’ – Deadline
With that said. The scripts of the final 2 episodes are already done and the titles were leaked.
Supernatural - Episode 15.18 - The Truth
Supernatural - Episode 15.19 - Inherit the Earth
Supernatural - Episode 15.20 - Carry On