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Dear @mrobbins, or anybody that can help me: I would appreciate if you could help me with the following question.

I need to study a circuit that has an impedance Z1 when its current I1 < l threshold, but drastically changes its impedance to Z2 when current I1> = I threshold. Is there any way to switch automatically by placing circuitlab elements in the studied circuit?

Is the V-I curve continuous? (Do the two piecewise-linear segments meet at a single V-I point?) If so we can figure out a way to do it. If it's not continuous, you're asking for trouble :)

What are the values of Z1, Z2, and Ithreshold?

Have you played with the relatively new Ideal Diode component https://www.circuitlab.com/blog/2020/08/10/ideal-diodes-in-circuitlab/ ? That's basically what an Ideal Diode is: a piecewise-linear resistor that transitions from very low impedance to very high impedance at a particular voltage (or equivalently current) value. (The underlying implementation in the simulation engine has to be careful to make sure the V-I curve of the overall device is continuous so that the simulation converges.)

In fact, you might be able to accomplish what you're looking for by using an ideal diode plus a resistor or two.

Great solution, dear @mrobbins I share this circuit, that I could do it with your contributions.

https://www.circuitlab.com/circuit/2bqhb343kg7a/using-ideal-diodes-as-impedance-switcher/

Thank you very much for your valuable collaboration. Best regards.