@PPQ Purple Scientific Method Ninjutsu or simply put Scientific Application in Ninjutsu, is what I call this method. It takes studious methods of Chakra Control and Nature/Shape Transformation, in the canon, this is advanced.
In the RP Era, it isn't because it's a modern approach. Here's what I allow as examples.
Fire can allow you to increase its temperature to make emission of blue flames and any other colored fire.
Wind can allow you to make solid air shields
Lightning gives you a degree of affecting your own bioelectricity to sharpen your senses.
Earth can make clay duh...
Water is what I have said.
What I do not allow:
Fire that can burn you to instant ash because only Amaterasu can do that.
Water that can purify anything.
Earth that is hard af.
In a nutshell, make your scientific app reasonable and what that means is, you must not reach Kekkei Genkai territory.
An example of Kekkei Genkai territory:
Hozuki water body, no matter how much of a Master you are with Water Release, you just can't replicate their feat.