With the release of 2024.1, a new property called "Shape" has been added to the PictureObject element, allowing to change the image's shape.
The following shapes are available for the Shape property:
In the designer, they look like this:
It is worth considering that the form is not attached to the picture but to the PictureObject. Also, for correct export to PDF format, you must disable the "Original resolution" setting, otherwise, the export may not be correct.