where I can find chinese grammar exercises

I suggest this website about Chinese Grammar with Rules and Interactive Exercises. The grammar is clearly explained. I use it and it is always good too have fun when learning. Have a good practice !!!
https://mandarinbean.com/grammar-points/

There are books, example, standard HSK shang and xia books that you can try. You can try which ever level you want to practice, HSK1 standard are a eaiser and and the levels increase as you go up to hsk5 or 6

在这里的PDF 下载中，你可以根据自己情况选择下载。有图解语法，HSK 语法......