To practice with this tense, please read the following and then answer the suggested exercises:

https://www.perfect-english-grammar.com/past-perfect-exercise-1.html

https://www.ego4u.com/en/cram-up/grammar/past-perfect-simple/exercises

https://test-english.com/grammar-points/a2/past-perfect/

https://elt.oup.com/student/solutions/preint/grammar/grammar_09_012e?cc=mx&selLanguage=en

https://www.really-learn-english.com/past-perfect-exercises.html

https://www.english-4u.de/en/tenses-exercises/past-simple-past-perfect.htm