Why On-off keying is a form of amplitude modulation, so the transmitted CW spectrum is set by how fast and how abruptly the carrier is switched. Faster keying means more sidebands: bandwidth is roughly the baud rate times a shape factor K, with K near 3 for soft, well-rounded keying and near 5 for hard keying. A typical 25 WPM signal with proper rise and fall shaping occupies only about 50 to 60 Hz, while sharp, square keying edges spread energy far wider as key clicks.
Watch out IF bandwidth and Q describe the selectivity of a receiver or filter, not what the transmitter radiates, and modulation index applies to FM or PM, not to on-off keyed CW. Output power changes how loud the signal is, not how wide it is.
CW bandwidth = speed x shape. Click-free keying means soft rise/fall; BW is about 4 times the WPM-derived baud rate.