This is a highly debated topic. Some people will tell you that 99% of leather in cars manufactured in a way that the surface of it is practically vinyl. If this is correct (and I believe it is), leather care products would have little effect. Some pro detailers recommend keeping it clean as the most important factor to keep it looking good and wearing well. You can research this.
After reading and trying too many products this is my conclusion as well. My opinion is based on little experience and no actual knowledge, so... My other conclusion is that most of the recommendations for leather care products are from people selling those products, or from people justifying their purchase. (Choice-supportive bias - we all do this to one extent or another.)
Last summer I tried 8 different products on the tan leather rear bench seat of my 4x4. I taped off areas and applied them all per directions. One of them took over 24 hours as various steps had to cure. When done, some were shinier than others. Some maybe felt different. Those differences seemed to disappear when I closed my eyes and had to use my fingers only. A week later I asked the wife which looked better and felt better. Small differences in appearance for a couple. No difference in how the seats felt to her.
The car is heavily used with teenagers in and out of it, and a 5 year old. It needs frequent cleaning. After being wiped down a couple of times with a damp towel I could not tell any difference at all. So what does this mean?
My guess is that all the products I use just dried on top of the vinyl-like surface of the leather and was removed when I cleaned the seats. But again, I don't really know.