To get fit enough to compete at a decent level in soccer - the first thing you should do is raise your base fitness up - this means lots of running and working hard.
When you've hit a good level of fitness - you need to then become
match fit
There are lots of theories on how to become Match fit,
HIIT is one, however the only proven one is
playing matches.
No matter how much running you do - you can never replicate the game fitness - including the jumping for headers, getting up quickly after being challenged/making a tackle etc.
But to become match fit, you need to be physically fit first.