My 2018 buick coolant every time minimum

Go to your local hardware or auto store and buy coolant, then pop open your front hood and locate the coolant cap. It should be marked with water drops or snowflakes. Then fill up the tank to the max fill level. Run the car for a little bit and drive around, and then check if the coolant is at the same level. If it is, you were just low on coolant. If it dropped drastically, then there is a leak in your coolant line, and you should take it to an auto repair shop.

@sukhpreetaulakh you mentioned "every time" which would mean to me that it happens frequently. Common issue could most certainly be a leak. Simple way to find a leak would be by pressure testing the cooling ystem. Depending on your location, you can find inexpensive radiator pressure test kits and perform the test yourself. It’s a fraction of the cost than what a service center will charge.

If it is not leaking then it is burning your coolant. That could be caused by (most commonly) a blown head gasket or even a cracked cylinder head. Cracked engine block is always a possibility but those have become less likely. For that you do want to check your sparkplug faces. see how your engine burns its fuel. Then you want to do a compression test and a leakdown test as well.

Let us know what you find out so we can try and help you to get this fixed.