GP doesn’t add any Lazy loader attributes to media images.
The google lazy load implementation is still experimental, so is behind the flag, so not a stable release just yet.
There is also discussions in WP Core about adding this feature / or version of to core. If this happens then it will automatically be pushed down to GP.
So probably a little way off before you see this being a core feature.
It was officially released https://wordpress.org/plugins/native-lazyload/ – seems like they are still deciding to put it in the core – I am using it on a number of sites – seems less bloat on scores and fast loading on Chrome – have not tested the numbers besides casually – I’ve been using my own version of Lazysizes https://github.com/aFarkas/lazysizes I believe there are a number of lazysize WordPress plugins