How can i increase the transmission power of 433mhz so that i can get more range, and which type of antenna should i use for non-LOS transmission anyone can help me please its urgent

RF antennas is not my specialty but I think this old post will help you: https://www.engineersgarage.com/contributions/increasing-the-range-of-rf-module-by-using-antenna-and-increasing-transmission-power-part-5-23/

Yes i read this post already and a little bit curious that the maximum supply voltage of the module is limited to 12 volt(transmitter) then how can this guy is using 18 volts to operate it it will surely distroy it and when he connected the 2 batteries is connected in parallel then how the voltage is halfed which is also wrong, the thing is that m missing the correct direction for this, every post i have read about is at some point of time is misleading so help me somehow or suggest me someother rf module which i can use with a non-microcontroller project. Thanks by the way for considering my request