Indeed you can, but an online test gives only an approximate result, which ideally later still need to be verified by an expert. You can’t examine someone’s pronnunciation and their reaction time to answer. With an online test you can check your vocabulary and understanding of grammar, but this is knowledge, not skill.
We have a test like that, check it out: https://englishpapa.com/test_anglijskogo/Taking this test does not cancel the trial lesson.