This is awesome:
I just putzed with this a little but it sure looks like the heat sink component accepts current as watts of heat and makes voltages scaled to degrees C.
There's also a thermal mosfet model but I couldn't get that to work.
Version 4 SHEET 1 1068 680 WIRE 256 80 64 80 WIRE 320 80 256 80 WIRE 64 128 64 80 WIRE 320 160 320 80 WIRE 64 256 64 208 FLAG 256 80 Tcase FLAG 64 256 0 SYMBOL SOAtherm-PCB 320 160 R0 WINDOW 0 37 -55 Bottom 2 WINDOW 3 -112 100 Left 2 WINDOW 123 -114 137 Left 2 SYMATTR InstName U2 SYMATTR Value2 Tambient=25 LFM=100 PCB_FR4_Thickness_mm=1.5 SYMBOL current 64 208 R180 WINDOW 0 79 35 Left 2 WINDOW 3 47 -17 Left 2 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName I1 SYMATTR Value PULSE(0 1 1) TEXT 591 154 Left 2 !.tran 10 TEXT 512 24 Left 2 ;Test of SOATHERM-PCB TEXT 520 80 Left 2 ;J Larkin Mar 17 2019