Can I automatically create a path around selected objects to create a boundary?

The boundary is created as a new object that can be used as a cut line.

Yes. 

Extensions>Generate From Path>Frame

Thanks for the answer.

I tested it here and there was a rectangle around the objects.

It doesn't go around the drawing, right?

it works with the combined bounding box of the selected objects.

If you just want a frame for the canvas. 

If you enable snapping, and snap to page. 

Then drag a rectangle from top left to bottom right.

Are you probably need an Offset like used on stickers?

Thank you very much!
The problem with the offset tool for me is that the drawing has a lot of details inside, I wanted to expand only the shapes that make the boundary without having to ungroup and select one by one.

In Corel there is a button that you click and it automatically outlines several selected objects. This boundary is created as a new object that can be used as a cut line. It would be awesome if Inkscape added this.

Thank you very much!
The problem with the offset tool for me is that the drawing has a lot of details inside, I wanted to expand only the shapes that make the boundary without having to ungroup and select one by one.

In Corel there is a button that you click and it automatically outlines several selected objects. This boundary is created as a new object that can be used as a cut line. It would be awesome if Inkscape added this.

There isn't a single step method but you can achieve this with a few keystrokes.

Select your shapes. Duplicate [ctrl+d]. Union [shift+ctrl+=]. Outset [ctrl+0]. Repeat the last step.

Another simple method is to draw a rectangle around your design as a frame and use the full bucket to fill the "inbetween" space. Delete everything you don´t need except the outline around your image - which can be offset/outset etc: