In a nutshell yes, assuming it behaves like Kia's existing EV models.
When using the brake pedal the car should start with regenerative breaking and add mechanical braking as needed (E.G. if you're breaking hard).
The advantage of using the paddles to brake is that it's all regenerative breaking but you don't get as much braking force.
Not entirely sure how one pedal driving is going to work in the EV6 as it's not available on existing models, it could well use mechanical brakes as well but my guess would be it relies on regenerative braking alone.
That all said there is absolutely nothing wrong with driving it like a normal car using just the pedals, many EVs don't have the paddles or a one pedal driving mode and still benefit from regenerative braking. Kia just give you lots of ways to drive.