You can adjust the sensitivity of 3D Touch on devices that support it.*
Go to Settings > General > Accessibility > 3D Touch and use the slider to select a sensitivity level. On the same screen, you can turn 3D Touch off and on.
* These iOS devices support 3D Touch: iPhone 6s, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPhone XS, iPhone XS Max.