There are people on here who have reported completing a soft landing successfully through a land border and turning around straight away back to the US. However people do this at their own risk and there is no guarantee will be successful just depends on the CBSA officers using some discretion and possibly the border not being too busy at the time.As posted above, I don't think they will allow same day turn around soft landing. They are allowing people to "enter Canada to permanently settle ".
For sure nobody should expect or plan for it to be easy so to be prepared to be questioned why need to soft land and some people on here have also reported being turned back without landing so approach as a 50/50 exercise. Attempting to do the same at an airport a whole different matter though and odds are lot less of completing a soft landing given in part the need to actually enter the country versus just a border post at a land border.