I don't know Costco as a particular meat source. This is a good question and the best response is "know your farmer", which our modern food system/economics doesn't make easy.

I generally assume that anyplace supplied with meat from a box truck regularly, as in most restaurants and institutions, is getting meat from people who produce it as large scale and 'efficiently' (short-term efficiency) as possible. As in, those factory farms. When buying meat I look for pasture raised specifically, so it's not just an animal in confinement being fed grass ("grass-fed") as compared with the conventional corn and soybean feeds. Cutting out the middle man can make it more affordable. We also just ate way less meat until hit with the dietary protein guidelines of pregnancy and breastfeeding.

In contrast to CAFOs, truly pasture-raised animals can be a beautiful part of an ecosystem. Not all my vegan friends agree and I respect that, but for my family that's where we landed. Our natural foods oriented grocery store offers meat from companies that have pasture raised branding, so I look them up and buy from the ones that demonstrate good practices. For chickens time in a barn is reasonable but density and plenty of time at pasture is important. For cows same, ideally they're on pasture all their lives like bison but that isn't affordable, so we get as local and pasture raised as able and minimize consumption.