For modifying the lk I needed some useless space closer to the required address range. So I utilised the unused function "aging test mode" that is present at the address 0x4c404460.
Then I modified those codes like this refer above image.
So normally it works like,

Some function ---> other function

This moded version works like,

Some function ---> my code ---> checks for volume up ---> other function

Modded and self tested (Realme Narzo 30 4G RUI3) by @antagonizzzt

Also check: recovery flashable zip