A joint of this thickness is very strong with the glue alone, assuming as others have said that the joint has no gaps. If it has gaps, biscuits may not help much.
A good glue joint is stronger than the wood.
If the two boards can be dry fit with no clamping pressure and show no gaps, then biscuits are not needed.
They can be used for vertical alignment, but I prefer dowels, since a dowel will give vertical and horizontal alignment.
If you have sufficient clamps, you should not need to use biscuits or dowels for this joint.