From a linguistics standpoint, there are some things you have with a native language that you don’t have with a second language by definition (e.g. native speaker intuition). By that metric, your second language cannot be native.

But it’s actually more complicated than that. I’d suggest there needs to be better definition on what counts as a second language for your question.

Brain plasticity as it pertains to language acquisition may (=depending on what study you cite) stick around until the late teens. That means that consistent and continued exposure to a language community will ultimately lead to acquisition if the learner/acquirer is not beyond the critical period threshold. If that occurs, you’d be a native bilingual (or multilingual), and you wouldn’t really have learned a “second language”. You would have two native languages, and in both you would have e.g. native speaker intuition.

This is kind of what you’re asking, but the issue is what is meant by “second language”. If you mean an L2 which was learned by someone after the critical period, then I’d argue that speaker would never be native in that L2 regardless of their proficiency. But if you mean an L2 which was acquired before thr end of the critical period, then by definition it is another native language, not a second one.