So what is your cone of influence? Well let's go back to the post about descending and the post about the attack position. Both of them work within your cone of influence. So let's start by breaking things down.
Your body has a natural centre of gravity and it is your hip area. Likewise your bike's centre of gravity is the bottom bracket (pedals). As in the other posts if you keep these two centres of gravity in alignment with each other then you should stay on the bike.
The bottom bracket forms the point of the cone, while your hips are the wider top of the cone. So you can move your body around and push the bike around within this cone and this is your cone of influence.
The best advice I can give you is to get out and ride a mountain bike, especially if you have come from a road bike background. You need to be moving around on the bike. Learning the basic mountain bike skills is all you need to catapult your gravel riding experiences.
As a side note, if you are from a mountain bike background get out on the road with your local club as the skills you will pick up there are priceless for gravel riding.
Gravel riding is a combination of both riding styles all you have to do is learn to read the terrain and adapt your style to suit.