LTSpice chassis ground or earth ground
Due to the nature of the SPICE (ever since 40+ years), the ground (0, GND) node is global, but just a net, like all nets. And all nets can be renamed to whatever name/label/etc is needed. In this case, that chassis you're looking for, in whichever SPICE software, is just a cosmetic appearance for a net/node, labeled chassis, or earth, or whatever. In LTspice there is only one cosmetic like that, called COM, but which has the same functionality of a common node (like chassis, earth, etc, unless mentioned otherwise). It, too, needs to be referenced to ground, so some connection is needed, if you so choose to use it. This is true for whichever SPICE program that uses those nodes as floating nodes. Here's a minor example of usage:



Note the R2 that connects the triangular shape ground (the ground, 0, GND) to the cosmetic COM. Its value is 1g to simulate a separate, floating ground, but really it's there with the sole purpose of providing a reference to ground without which the solver cannot calculate. Also, the plot shows V(2,COM), which is just a local reference for probing; can be anything, really.