There are a few key specs to look out for in a modern gaming phone. The main one is the core chipset. Look for a Qualcomm Snapdragon chip that begins in '8' - the latest are the 8 Gen 2 and 8+ Gen 1, but the previous 8 Gen 1 will still do great too - or a similarly powerful MediaTek Dimensity chip like the 9000 or 9200. You'll also want at least 8GB of RAM to make the most of the chip - more is better, but there are diminishing returns beyond 12GB or so. The display matters too. You'll probably want a fairly large screen to game on - at least 6.5in - and look for one with a 120Hz refresh rate or higher, and the fastest touch response rate you can find. Spending more for AMOLED tech over LCD will deliver better contrast and colours, but don't worry too much about resolution - gaming phones rarely go beyond Full HD.