I use "Leather Honey" cleaner and the conditioner. It is a little pricey for leather care, but it is worth it. You may need to use the conditioner several times to bring back the leather if it is old and dried out. I suggest putting on the conditioner as directed and leaving sit over night. If it soaked in the leather you will need to reapply until it doesn't absorb any more. Then you only have to clean and condition every six months.

Thank you for the information. Does it also deodorize a bit?

Any lingering odors from previous owners are mild but I’d like to remove them and just leave a natural leather smell. They were very clean but there was that occasional cigar smoke and it is noticeable, although faint. It really doesn’t bother me. My spouse feels differently.

I really don't know if it deodorizes. The odor could be in the cushion filling and not the leather. You have to watch out what you use on leather. The cleaner might take care of some of it. When it is nice out I would just let the window open and let it air out. You might try putting some kind of odor absorber under the sofa. I don't think dry baking soda would hurt the leather. I would try sprinkling it on the sofa, letting it sit for a day and then vacuuming it up with a brush attachment before you clean and condition it.