How to operate 1602 LCD on 3.3V
It might be possible to use it at 3.3v. Usually the chip itself will work at 3.3v but the liquid crystals in the LCD glass may needs higher voltages. It might be possible to give negative contrast voltages to drive the glass better, but the glass supply voltage biasing may not be optimal. There is no module type code or a link to a datasheet so it is not known if using it with 3.3v is possible at all. There are 3.3v modules which generate negative voltages onboard so the can be used just as easily as 5v modules.