Breakout cables typically split to 4.

e.g. QSFP28 (100GbE) splits into 4x SFP28s (25GbE each), because QSFP28 is just 4 lanes of SFP28.

Same goes for QSFP112 (400GbE). Splits into SFP112s.

It’s OSFP that can be split in half, i.e. into QSFPs.

Here’s an example of the cables I was referring to that can split a single 400Gbit QSFP56-DD port to two 200Gbit ports:

https://www.fs.com/products/101806.html

But all of this is pretty much irrelevant to my original point.