Depends on the child. My 14 year old still forgets these things, so he uses brown bags for lunch and no longer owns a coat.
My younger kids are 6 & 8 and this has never been an issue for them, so clearly some kids manage to master this skill.
I would try two things - one, label everything and have two of everything. So if she forgets her lunchbox on Tuesday, you have one to send in on Wednesday. Same with light jackets at this time of year, when it's warm enough in the afternoon for a child to forget and not every child is bringing one to school. In the winter it's usually less of a problem because the teacher will incorporate "put on your jacket" into the afternoon routine because it will be cold and everyone will be expected to be properly dressed.
Second, create a reward system - this would be the perfect opportunity for a sticker chart or an immediate positive consequence. For example, if she remembers her lunchbox and jacket, she can play a game on the computer for 15 minutes or have 15 minutes of extra time doing whatever she likes most. If one or both is missing, no bonus time. If she remembers X number of days in a row, she gets a treat - in our house, it might mean that we go to their favorite playground that's a bit of a drive from our house, or that instead of having pizza on Friday night, I'll pick them up Taco Bell (nasty but they love it). Give her positive reinforcement for remembering, don't punish her for forgetting.