Not a flat 12 like the Testarossa had?
According to Ferrari, that engine is a “180-degree V12.” :)
And unlike, say a VW flat four or Porsche flat six, each pair of cylinders shares a single crankshaft throw - an arrangement Porsche also used in the flat-12 that powered the 917. Using a separate throw for each cylinder would result in a longer engine, and in any case it isn’t necessary since such a 12-cylinder engine is basically two inline sixes sharing a crankshaft.