To have the crispiest french fries, buy your frozen french fries from a larger store that sells a lot of frozen french fries. If they are on sale in the weekly ad, even better, because they will be fresher. The store will have to get in extra stock for the advertised sale, so it is new stock. Smaller stores often have the worst frozen food because they sell less, so stock sits in the freezer longer getting covered in those ice crystals which will make your fries soggier when baked and also makes them taste freezer burned. Also, larger stores tend to have more efficient freezers because they can afford better equipment and maintenance.
Get those fries home quickly. Keep a small cooler in your vehicle if you can, for frozen items, or bag all your cold groceries in one bag so they keep each other cold. Get them in the freezer right away when you get home. Defrosting and re-freezing can give you soggy fries.
When you bake your fries in the oven, be sure to pre-heat the oven all the way to the specified temperature and when you put the pan in, don’t linger with the door open too long or your temperature will drop. Put your fries on the pan when the oven is ready - don’t fill the pan and then pre-heat the oven while your fries sit out on the counter for 15 minutes. Spread them in a single layer. When the baking time reaches the half way mark, grab a spatula, an oven mitt, and get in there and flip the fries on the pan. If they are the shoe strings, don’t try to flip each one individually or you will be at it all day - just lift and flip in sections and do your best - quickly - so the oven stays hot.
If you have an electric oven with the top broiler elements, you can turn on broil for the last few minutes to give more crispiness, especially if time is up and they do not look golden. DO NOT WALK AWAY. DO NOT LOOK AWAY. EVER - when you turn that broiler on or you WILL regret it. It can take just two seconds for your food to turn from golden to charcoal under those elements once they are cranking. My last broiler lesson (and I know better) was toasted coconut. My kitchen stunk for hours.
When you take the fries from the oven, transfer them to paper plates or towels if you want to avoid any further moisture seeping in from the fries cooling off on a metal pan.
I don’t know if it is cool to name brands here, so I won’t, but there is one frozen fry brand that uses the word crispy in the name and they are definitely crispier than the same style fry that does not say crispy. I think they are crinkle cuts. Red bag.