What is Blend Curves Command and how to use it in AutoCAD?

To create  a curve between two curves. 

if two curves are not joined together.

Creates a spline in the gap between two selected lines or curves.

Select each object near an endpoint. The shape of the resulting spline depends on the specified continuity. The lengths of the selected objects remain unchanged.

Valid objects include lines, arcs, elliptical arcs, helixes, open polylines, and open splines.

The following prompts are displayed.

Continuity

Specify one of two types of blends.

Creates a degree3 spline with tangency (G1) continuity to the selected objects at their endpoints.

Creates a degree5 spline with curvature (G2) continuity to the selected objects at their endpoints.

If you use the Smooth option, do not switch the display from control vertices to fit points. This action changes the spline to degree3, which will change shape of the spline.

The BLEND command joins Fillet and CHAmfer, offering another method for creating transitions between2D drawing objects. Whereas CHAmfer creates beveled corners (that is, straight lines), and Fillet creates round corners (circular arcs), BLEND corners are spline objects. Choosing the Tangent option produced the red spline, and choosing the Smooth option produced the blue spline..

The BLEND command is found on the Home tab of the ribbon > Modify panel > Under the Fillet/Chamfer dropdown, there is the new blend tool. will let you select two objects and from their endpoints, this command will create a spline that is tangent from their endpoints.

The power of this tool is that the endpoints don’t have to be a natural continuation. Otherwise, the Fillet command would suffice. One tip that I figured out with this command is that after you select the first object, if you hit the up and down buttons, you can toggle between the possible final endpoint.

Here’s how:

BLEND <enter>

Select near the endpoint of the first object.

Before you select the second object, hover over it and you will see a preview of how the final blend will look. Select the second object.

I sow the previous answers from experts and I support their answers