Extreme Planetary Features vs realism

[Ghostman]

woth Larger than Earth or Smaller than Earth size

How would change gravity ? would be possible somehow to have the same Earthlike gravity?

If the planet's density is the same as Earth's, then larger size results in stronger gravity on surface, and smaller size in weaker gravity on surface. It is possible for the surface gravity for a different sized planet to be comparable to that of Earth if it's composed from more/less dense material, although this is only feasible to some limit.

With No tectonics

Like Mars , woul dhave no orography , no mountains? what woudl happen? to Magnetic field perhaps?

Mars does have mountains. It's largest mountain is much bigger than Mt. Everest.