The Apple iPhone XR uses the hexa-core Apple A12 Bionic 7nm and has 3GB RAM. The A12 delivers top notch performance, for demanding apps and the latest 3D games. There are newer Apple iPhones with faster processors, however the speed difference won't be noticeable with everyday usage.
The 3GB RAM may start to show its age when it comes to multitasking, particularly when running games. However, Apple's software optimisation minimises the amount of times apps will need to reload upon reopening.