The winger penned an 18-month contract with Blues in January 2017 after impressing during a loan spell from non-league Beaconsfield.
McCoy, who was still only 18 when he joined, went on to feature regularly in Blues' Under-23s side during their eye-catching end to the 2016/17 PDL2 season.
He chalked up a total of 20 appearances, netting twice, as Richard Beale's side won seven of their last nine games to catapult up to fourth in the final league table.
During the 2018/19 campaign, McCoy made a further 31 appearances, where he was instrumental in helping to the Development Squad to the PDL North runners-up spot and the Final of the National Play-Offs.
In the summer of 2019, he signed a new 12-month deal.