How do determine MOSFET parameters in LTSPICE
To determine a parameter from simulation you start with the fundamental definition for that parameter. For the output impedance we have rds==Del(Vds)/Del(Ids)|Vgs=constant. Set up your simulation at the DC conditions on the circuit-- VGS and VDS. In series with VDS insert an ac generator, vds, and monitor Del(Ids)=ids, the small signal response. Now the ratio of the small signal response to the small signal excitation, gds=ids/vds, the reciprocal of this is rds.
For gm use its definition: gm=ids/vgs|vds=0; gmb=ids/vbs|vds=0,vgs=0 where vbs is the body to source small signal potential.
Magnitude and phase are found using calculator functions if not directly enabled in your plotting tool.