Two-dimensional double perovskites have experienced rapid development due to their outstanding optoelectronic properties and diverse structural characteristics. However, the synthesis of high-performance multifunctional compounds and the regulation of their properties still lack relevant examples. Herein, we synthesized two multifunctional compounds, (C6H14N)4AgSbBr8 (1) and (F2-C6H12N)4AgSbBr8 (2), which exhibit high solid-state phase transition temperature, bistable dielectric constant switching, second harmonic generation (SHG), and bright emission. Through H/F substitution, the transition temperature increases and achieves a smaller band gap attributed to reduced interlayer spacing. Furthermore, we investigated the broad emission mechanism of the compounds through first-principles calculation and variable-temperature fluorescence, confirming the presence of the STE1 emission. Our work provides insight into the further development of multifunctional compounds and chemical modification that enhances compound properties.