With very few exceptions every school accommodation I’ve heard of is something that every student should have access to, diagnosis or not.
One of the most common accommodations is extra time on tests. Time limits on tests should not exist. Most tests are designed in a way that the average student will have plenty of time leftover, and anyone who needs more time should be allowed that time.
If disability accommodations help you, you should have them. Full stop. If you don’t need them, you won’t find them helpful in the first place. Extra time on tests isn’t helpful to someone who completes them on time.