Can I use low color contrast in native mobile apps? Android & iOS have high contrast modes

I design native apps for Android and iOS. Both Android and iOS have high contrast modes. With this in mind, can I use low-contrast colors (say, 3:1 instead of the 4.5:1 that WCAG Level AA requires), knowing that users with bad eyesight can turn on the high contrast mode?

And a detail question related to compliance with the WCAG: Do these high contrast modes count as "assistive technology"? (The WCAG say that content should be readable by people "who do not use contrast-enhancing assistive technology". Source)