There are a few options for taking your dog with you on bike rides. You can use a hands-free leash, but this might mean too much running for some dogs or not safe on some roads. The main alternative to dog baskets is trailers. Dog baskets work for small to medium dogs, and rear baskets for slightly larger ones, but for anything bigger, you’ll need a trailer. The maximum you can take, even on a rear basket is probably about 25 lbs. It’s really important to think about your safety with the extra weight on the front or back of the bike, as well as your dog’s comfort, as baskets will only be available up to a maximum size.
There are also considerations with trailers, you’ll have to be confident on your bike, maybe more so, because you’ll be double the length you’re used to, and trailers move somewhat independently. If you have a small to medium dog, a basket will be easier to get used to.