You first need to reach Tier 3 — this is the tier where creators get a creator code. Then you can approach and ask about it. Or perhaps you can contact Supercell directly.
This is mostly a scale issue — are you serving an app for millions of users or will it only be used by friends / family? I don’t want to make any assumptions about what you are planning to build, but if it’s closer to the latter, the chance of you getting this level of access is highly unlikely.