First check your course guide to see whether (and in what way) you may use GenAI in your course. In case there is no information in your course guide, using AI to generate the content of your assignments is considered fraud.
QuillBot (https://quillbot.com/) is an AI tool that is specifically designed to improve your writing. While using its paraphrasing tool, that QuillBot is most famous for, is not allowed in your academic assignments, you could use its grammar checker for improving the fluency of your writing. See an example in figure 9 below: