in CQB situations headshots can be necessary and practical, but we are talking about ranges where you do not have space to fully use your iron sights or where a standard rifles zero distance is too far away for the sights to be effective (there are aiming techniques with AR platform rifles for ranges under about 50 meters where you line up the front post with the top of the rear sight ring instead of the center, and aim that intersection at the target's head, but this may only work on full length ARs or with certain sights and gun setups). at extreme CQB ranges the incidental or post-death firing of the person you just shot actually has a realistic chance of hitting you, and operating in CQB you often have to be careful with your shots to avoid hitting civillians or hostages (through walls or in the room) making rapid or automatic fire a poor choice in certain situations. if you are not worried about civillians or infrastructure you simply don't do door-breaching SWAT style CQB, you chuck grenades or a satchel charge into the building or light it up with the .50's from a mile away or call in a mortar strike or something.

however when shooting at someone from range like this, you should definitely aim center mass, unless you are like a GIGN sniper trying to take out a target with a hostage or a detonator, then you aim for the brain stem, but most SWAT style sniping is done at close range, not more than across the street of the target building, and with a scope.

but if we are being real, sniping or shooting at all is a poor way to assassinate someone. to ensure the target is eliminated, the CIA for example recommends explosives deployed from close range (i.e. strap a brick of C4 to them, shove a grenade into their mouth, etc., just throwing or launching a grenade in the room isn't always enough) or blunt force trauma to the head.