Does this imply killing the opponent is a viable strategy in chess?
Murdering your opponent will almost definitely be considered a rule infraction.
Although there might be some edge cases if the murderer was an absolute ruler of the current country. Or maybe if you happened to kill your opponent in self defense somehow.
You mean like King Canute of Denmark, England, and Norway? [0]
[0] https://wegochess.com/complete-timeline-of-every-chess-relat...
You sacricifive your next dozen or so free years for the victory.
A high ego grandmaster on the decline may decide loss of the remainder of their freedom in life is worth the sacrifice.