Lots of different ways are used and which is better depends on many things. One way to do it is a hose from the faucet to the tankand that does avoid carrying water. But the water does need to match the tank for temperature as well as any changes you may make to the water. If you adjust things like PH. GH or GH, you will need to use care to avoid abrupt changes in those levels in the tank. The temperature is the one many get wrong as they get too much hot or too much cold water from the faucet. It is easy to start the flow at near the right temp and then in a few minutes find it is way too hot. CAREFUL!
Also adding the water directly to the tank means we need to adjust any treatment we do to remove chlorine or chloramine from the tap water. If we treat the water in a bucket before adding to the tank, we can use the volume of treatment to match the bucket size but if we treat the water after it is in the tank we need to use more so that it meets the tank volume rather than the bucket.
So we have to judge which is best for us. Some will not want to carry buckets and use more water treatment. Others may be okay with the bucket carry and use less and be somewhat safer to get the temperature, etc. correct.
I use a plastic barrel, use tubing to fill the barrel and let the water come to room temperature and treat it. Then after a day or so, I use a small pump to moveit from the barrel to the tank.
Many ways but which will work best for each of us??