(Java Minecraft 1.14.2) How to make a charged creeper do more damage without increasing explosion radius or summoning multiple?
Solution 1:
You could summon an area effect cloud in the same position as the creeper. This command would do just that:
summon minecraft:area_effect_cloud ~ ~ ~ {Potion:"minecraft:strong_harming",Radius:1.5f,Duration:6,Particle:"minecraft:explosion"}
If the affected area for this is too large, then you can simply decrease the Radius.