OK. Let’s see if this is clear enough.
Here’s a view from the inside corner.
From left to right.
Draw half of the leg and make it a component. Radius the inside edge with RoundCorner or FredoCorner. On the right in the screen shot below, you can see this component also has the radius on the outside corners as well.
Copy, flip and rotate the component to make the other half.
Miter the components–you only need to edit one for this. Draw a line at 45° on the top and push the triangular face down to the foot of the leg.
Hide the seam line edges with the Eraser tool while holding Shift.
A view from the other side.
And a closeup of the outside corner of the leg.
If you want you can combine the leg parts into a single component but I’d leave them separated.
If you want to make them one piece with the top as in your original, make sure the leg components are solid and add a box for the top as below.
Then use Outer Shell to combine them into one group. I’d make that a component after Outer Sheel.