First of all, if you live close to the border like me you are fucked and you WILL have to leave your house and move closer to Germany or become a displaced person like me. First few days will be the worst days you could ever imagine. In my case the war started in winter so we were sitting no gas, no light, no food just in a dark cold rooms with just candles to warm us up. Every 5 minutes there were jets flying over your house and bangs really loud like couple kilometers away. You could also hear constant noise of people shooting far away. It sorta sounded like thunder a little bit.
You will most probably also experience the worst shit ever: when you lay down on bed sleeping and then you wake up and the whole house is shaking because of the missile nearing you. And you don't know if you're going to die this moment or not.
You won't be able to go out past 10 pm because of curfew if you live close to the border. Your father will probably get drafted unless he's physically unfit for service. A lot of people will volunteer at the start of the war, but the things will get down real quick after couple years. Poland would likely not be in NATO anymore because NATO would fear escalation and kick Poland out(or it will be somehow played around so that NATO wouldn't have to get in the war). A lot of your friends may literally die because of a drone strike on their house. People and animals dead on the streets. Bloodshed in the city center, burned out houses, people screaming in agony and despair mourning their dead relatives. Children who won't see their father lost on the frontlines.
If you will become a displaced person like me you will be practically torn apart, because after a small amount of time time you will miss your home and will want to go back. Things would feel out of place.
I personally got anxiety, depression, PTSD and derealization/depersonalization syndrome because of all that, I don't know how you would go through that, but that's my story.