Yes, you can tell it that you are learning the language at the beginning of the conversation in plain English and ask it to correct any mistakes. You can easily start a bilingual conversation with ChatGPT, some random example here: https://www.reddit.com/r/russian/comments/112xgp2/practicing...
To show you what I meant when I mentioned "enriching sentences", I've just generated an example of a B1-level English sentence improved by ChatGPT.
User: Please improve this sentence: "Many people want to learn languages because they like to travel"
ChatGPT: "Learning languages is a popular pursuit because it enables people to travel and explore different cultures with greater ease."
It works similarly with other languages.
As for my German level, it wasn't evaluated by ChatGPT but by an external assessment exam and I only mentioned it to add some more context to the story. Frankly, I probably wouldn't trust ChatGPT's assessment in this regard.