You can set up your landscape to write to a Runtime Virtual Texture, make a new material that samples the RVT (plug whichever channel of the RVT into Emission for best results), and then use the ‘Draw Material to Render Target’ Blueprint node to bake that material to a render target, which you can then do whatever you want with.
If you want the different maps (Base Color, Normal, etc) you’ll have to either shuffle the wires around in the material and re-bake, or set up a different material and render target for each map.
Obviously, the final texture resolution will be limited to the maximum render target resolution (also if your camera is too close to the landscape when you bake you might get areas of the baked texture that are more detailed because the RVT has loaded higher res tiles nearer the camera, so be careful about your camera placement).
[edit]Alternately, you can set up the material to sample the RVT channels normally and assign the material to a static mesh asset (like a plane) and use Asset->Bake Out Materials. Pick whichever channels you want textures for and a resolution (up to 16k, but you’ll need a lot of VRAM for that) and bake the material out that way. You’ll then have to Save As… the material and textures in order to make them visible in the content browser so they can be exported or used on other meshes because Unreal hides the baked assets for some reason.