If we change K factor of sprinkler from 5.6 to 8 size of sprinkler also will be change from 1/2 in to 3/4 in Please advise ?

the equation used in calculating K factor:

so it depends on the flow and the pressure

for same pressure rate you have to change the size of the sprinkler

for some models you can keep your sprinkler the same if you change the flow and pressure

finally you have to check the product catalogs

Thanks and appreciate your time