Is it possible to increase the prune size and get bitcoind to pull previous blocks? for example, currently its:
  &quot;size_on_disk&quot;: 32084546902,
  &quot;pruned&quot;: true,
  &quot;pruneheight&quot;: 650668,
  &quot;automatic_pruning&quot;: true,
  &quot;prune_target_size&quot;: 67108864000,

Is there a way to decrease the pruneheight? I need the prune height to be 630000.
I increased prune=64000 from prune=32000 but from what I can tell it will just store more blocks going forward?
Bitcoin Core doesn't have such a feature. The prune depth controls how many blocks are kept, and you can change that (-prune=N option on the command line or prune=N in bitcoin.conf), but once a block is pruned, it is gone. If you want to add blocks back, for now you'll need to resync from scratch.
There is no technical reason for this; it's perfectly feasible to implement a mode where desired old blocks are refetched and inserted into the blocks datadir again, but this simply isn't implemented at this point.