//1.if(entity == index) //index is the entity's index you want to change model
//2.if ( StrEqual(classname, "classname")) //change "classname" to the entity's classname which you want to change model
Because it is not a complete code, I'm just explaining the usage.
You should choose one way to remove the "//". not remove "//" mean's change all the entity's model.
If you choose 1 mean only change one entity, index is the entity's index.If you choose 2 mean change a type of entity, "classname" is this entity's name. And you should change the index or "classname" by actual situation.
Because I don't know which entity you want to change. I don't even know which game you want to use.