Walker signed for City in a £50m deal from Tottenham Hotspur last year, winning the Premier League title and the EFL Cup in his opening campaign.
The Englishman played a key part in the Citizens conceding the fewest goals in the league last season, but Walker has admitted that Pep Guardiola has changed his role in the side as City begin their title defence.
"My role is a little bit different, where I am tucking in a little bit more and trying to control people," Walker told reporters.
"I still have the licence to go forward, but now I'm getting older it's probably more about picking and choosing my runs, rather than up and down the wings as I was at Tottenham!"
Walker's City will host Newcastle in their next Premier League game on Saturday evening.