@User try to run xschem outside of the xschem_sky130 directory, and load this example:

ngspice/led_driver.sch

. there is an ideal switch

devices/switch_ngspice.sym

, may be you can use it. The diode has a 'swmod' model where you control the on threshold, hysteresis, ron, roff and so on. The model looks like:

.MODEL swmod SW(VT=0.1 VH=0.01 RON=0.01 ROFF=10000000)