A Quartus Tip:

Most of the primitives allows modifiable input/output width. for example, you can use a 16-bit bus as the input of a not gate.
The only requirement is that the bus width must match. If the input is 16 bits, the output must be 16 bits.
For multiple input gates (and,or,xor...), The width of each input and the output must be the same.
For tri-state buffer: input and output buses must have the same width. The control signal must be 1-bit.

-Guangyu