By using time() function in PHP
time() return current timestamp and by adding 10 day's second to it lead to time of after 10 day time
add 10 days to the current date.
date('Y-m-d',time()+3600*24*10);
add 20 days to the current date.
date('Y-m-d',time()+3600*24*20);
add 30 days to the current date.
date('Y-m-d',time()+3600*24*30);
By using strtotime() function in php
strtotime() function convert string to time .
add 10 days to the current date.
date('Y-m-d',strtotime("+10 days"));
add 20 days to the current date.
date('Y-m-d',strtotime("+20 days"));
add 30 days to the current date.
date('Y-m-d',strtotime("+30 days"));
add 10 days to any date.
date('Y-m-d',strtotime("2021-10-19 +10 days"));
add 20 days on any date.
date('Y-m-d',strtotime("2021-10-19 +20 days"));
add 30 days to any date.
date('Y-m-d',strtotime("2021-10-19 +30 days"));