Whether or not a body is in a house or outside won't affect whether a bullet overpenetrates the body.
All else being equal, you'd expect higher velocity JHPs to penetrate less because they tend to open (mushroom) faster and bigger, creating more resistance through a fluid medium -- read: "the guts of the guy who got shot" -- and therefore losing inertia in a shorter distance.
However, "all else" is never equal and bullet design plays the biggest role in determining a round's penetration.
While overpenetration is a legitimate issue, within reason it is not a primary concern. A bullet that is adequate to reach the vitals on a large muscular man will also easily overpenetrate the fleshy part of an arm. And a simple truism is that in a fight sometimes shots miss their target, and a miss is essentially a complete "overpenetration" since the bullet is going to keep going. What this means is that you have to be cognizant of your target and what is behind him, even in a defensive encounter.
Regarding the effects of shooting indoors, any JHP that is adequate for personal defense will also penetrate through just about any normal interior building materials. There are some gimmick rounds on the market which claim to be safe from this, but such rounds are generally regarded as insufficient and ineffective at performing their primary duty, which is making people FDGB when shot.
There's obviously a lot more to this and yes some rounds will have a greater chance of overpenetration than others ... but stick with the recommendations you're seeing here, maximize your practice time, get the best training you can, develop a strong mindset and you'll be way ahead of the curve.
