This is determined by the max-std-op-returns-count blockchain parameter. You can set this to up to 1024 if you are creating a new blockchain, or use the upgrade mechanism to change it on an existing one:
https://www.multichain.com/developers/upgrading-nodes-chains/
Please note that, to prevent abrupt changes in blockchain performance, each upgrade can no more than double this parameter from its previous value. So you might need to use a few upgrades in a row.