While there is no direct command to sweep a device parameter during simulation, you may use a script to emulate such behavior. The example input file contains of an resistive divider with R1 and R2, where R1 is swept from a start to a stop value inside of the control section, using the alter command (see 17.5.3).

Input file with parameter sweep

parameter sweep
* resistive divider, R1 swept from start_r to stop_r
VDD 1 0 DC 1

R1 1 2 1k
R2 2 0 1k

.control
let start_r = 1k
let stop_r = 10k
let delta_r = 1k
let r_act = start_r
* loop
while r_act le stop_r
  alter r1 r_act
  op
  print v(2)
  let r_act = r_act + delta_r
end
.endc

.end