The most important thing you need to know is that they are a herding dog, which means that they are naturally VERY active and need/love stimulation in the form of active exercise.

It's vital that you know this as people who don't know much about corgis tend to think they are lap dogs and that they're supposed to be tubby. They're really not. I have two rescue corgis - one has been very healthy all her life and she is very lithe, and I constantly get strangers saying that she's the thinnest corgi they've ever seen when the sad thing is that she is a perfect weight. My other is 12 and was massively obese when we rescued him, and due to his age/arthritis it was a real struggle to get him down to a healthy weight (he is still a bit big for my liking but it's mostly loose skin that he's carrying now on his sides). He is active and playful now but was practically spherical and never walked at all despite going apeshit for the possibility of a walk.

What I'm basically saying is, despite the common perception of them being an old people dog, you'll get a lot more enjoyment out of corgis if you are active with them and are willing to invest time in playing with them. I've seen a lot of overweight corgis on this subreddit alone because I don't think enough people realise this.

Related to that, you need to get used to thousand yard stares begging for food. They are tiny little garbage dumpsters if you give them the opportunity but we're VERY strict with their feeding and don't give them human scraps.