First, don’t forget to review material on Professor Messer’s channel on Youtube.
Next, do a good Google search for Free CompTIA Sample Tests and Questions.
Good Resources
ProProfs (https://www.proprofs.com/)
ExamCollection (https://www.examcollection.com/)
ExamCompass (https://www.examcompass.com/comptia/a-plus-certification/free-a-plus-practice-tests)
Terrible Resources
Any source that has “braindumps” in the URL or on the pages is awful. They are highly likely to lead you astray, until your knowledge is truly deep.