20MHz Channels are enough to meet all band width requirement.
In fact, the 40Mhz channel is bonded via 20+20MHz channels.
Please check the below table and bonding regulations. For example, if you select Channel 48, Channel 44 and 48 will be bonded together for 40MHz channel 46. And you may select the range of 20MHz channels for the 40MHz channel plan according to the rules. Ex: Range 36,40,44,48, it will be 40MHz channel 38,46.
With the same rule, you may understand how to apply 80MHz, 160MHz channels setting for 802.11ac wave 1 and wave 2 AP from 20MHz channels according to the below table.