They don't always swell. I've procured several hundred dells and lenovos over the last decade, maybe 5% swell and it's usually ones in the same batch when they do it.

There’s a higher chance of an eBay replacement battery swelling. Ask me how I know.

I removed the battery form an old laptop that wouldn’t hold a charge for more than a few minutes and it’s instantly half the weight. It always has to be plugged in though

sure, but that chance exists with any lithium ion battery. if you don't want to just toss the battery and keep it plugged in when you use it, then limit the charge to 50%. that will prolong whatever life the battery has left in it.

Can you set a battery charge limit? If so then cap it at 80%. The less charged they are the less likely they are to expand.

A cheap knockoff battery is FAR more likely to expand than a legit official one.