See Models · JuMP
It’s just:
model = Model(Clarabel.Optimizer)
write_to_file(model, "my_model.lp")
p.s., You’ve somehow found an old version of the MathOptInterface documentation Here’s a link to the official JuMP documentation:
https://jump.dev/JuMP.jl/stable/
You can also get there by going to https://jump.dev and clicking the “Documentation” link at the top.