How can i make this grid larger? my spaceship is already this big.
when i teleport to a place outside of this grid, i will be stuck and can`t move… 
That grids bounds represent the world bounds(the safest area before your game’s physics and lighting goes nuts) which is about 20kmx20km. 1 Unreal Unit = 1cm so you may want to rescale your ship to real life size. If you dont want or care about any of this just disable Enable World Bounds Checks in World Settings.
I was thinking about that, i have just maxed my green grid to 255 quads by 255 quads, and 2x2 sections, and 32 x 32 components giving me 8192 resolution then i will create then create a lightmass importantce, okay 1 landscape floor do, so what about where management button next to sculpt click on that then click on create new landscape then should duplicate move green grid across then click on create now should have 2 created the same size, then carefully align 2 together if that will help good Luck, mega ocean mega islands.