Impact of acid-amine equilibrium for triggering the formation of CsPbBr3 platelets and subsequent long-range self-assembly as a function of acid concentration is reported. The study was performed by treating Cs precursor followed by oleic acid to the ongoing process of L2PbBr4 layered perovskites formation at room temperature, and this led to the thinnest possible platelets of CsPbBr3 with one atomic layer of Cs insertion. These platelets form self-assembly in the micrometer range, and this ordering was tuned as a function of oleic acid concentration and reaction time. With evidence obtained from in situ live monitoring by optical microscopy of these assemblies during the ongoing reaction in solution and analyzing the collected samples ex situ by electron microscopy, it was established that these long-range 1D organizations of platelets took place in solution. Details of the insights of the formation, self-assembly, and impact of different reaction parameters in the formation of these platelets are investigated and reported in this Letter.