Whatever the type of soil, it is always risky if you don’t make a hole
in the ground first,
as failure to do so may make the screw move around during installation which
will damage the soil around the screw.
This could force you to install the screw in another location (at a minimum distance of 50 cm) which can be very problematic.
In addition, the hole helps to guide the screw during installation and therefore puts less pressure on the installation machine.
Finally, pouring water into the hole helps to lubricate the position of the screw and therefore to improve its installation.
You can adapt the diameter of the hole to the type of soil.