Hello
The fans can only be connected to the power supply. Control of the RGB has the case a button because they are already connected to a hub that still has free places. But yes, with an extension/adapter everything can be connected to the mainboard.
I bought this configuration:

MSI MPG Z390 Gaming Pro Carbon
AIO Enermax Aquafusion
And the case.
Thanks to this configuration, I wouldn't have to buy any additional accessories.
Adapters and cable extensions are all included👍