In a war film, sometimes a soldier will be thrown up into the air by an explosion, or a grenade will go off, and when it is over, they will be missing arms or legs. How do they make the soldiers with missing limbs in war movies look so life like?
They employ amputees.
Silicone prosthetics and lots of corn syrup with red colouring in it for the 'ragged bleeding edges'.
There are - unfortunately for the individuals, but fortunately for the movie industry - a large number of ex-servicemen and others who are more than capable of still looking good running & shooting across a film-set battlefield wearing their own real-life prosthetics, then take them off and have them replaced with 'blood, guts and gore' for the 'dying in a splash of filmic action' for the entertainment of the cinema audience.
The intermediate 'flying in the air' section will have been done by a trained stunt man.
If it's a principal who in real life has a full set of limbs, they may resort to the old 'strap their arm up their back' technique, or 'leg buried inside the hospital bed', or more frequently these days... a green sleeve and CGI in post - see Colin Farrell in Dumbo - green sleeve + CGI. Backgrounds were done with blue screen, so post could more easily differentiate.