Periodically Poled Piezoelectric Film (P3F) stacks have gained attention as a promising platform for the next-generation RF front-end acoustic filters that extend into cm-and mm-wave bands. By demonstrating the potential for developing high-performance acoustic devices with frequencies of up to 20 GHz, LN-based P3F structures have opened up new possibilities. In this study, the influence of key parameters such as the number of layers, LN orientation, duty factor, and variation in thicknesses between the layers on the efficiency of n-th harmonic excitation and spurious modes was examined. To enhance higher-order harmonics, which are suppressed in P3F structures, a novel multilayered stack with Aperiodically Polarized Piezoelectric Films (APPF) is proposed. Optimizing the ratio between layer thicknesses can enhance any higher-order harmonic. Three-layered 128°YX LN-based APPF structures optimized for the generations of modes A3-A17, with electromechanical coupling continuously decreasing with frequency, are described. For example, A5 and A7 modes with coupling coefficients of 16.3% and 9.5% can be generated in APPF structures, thereby filling the gap between 32% of A3 mode and 6.2% of A9 mode generated in P3F stacks.