In this sentence you say that you will show them something they are likely to already have (in their possession). It is not really clear, you could change it to, for example: "I'll show you something that you'll want for sure." In this sentence you are saying that you will show the person something that you know they want to have 100%. I hope I helped.

If you want to say that it’s 100 % sure the person want something, then you can’t use the word “likely”. “Likely” expresses there is a chance the person will not want to have it. “Likely” means ”probably” or “probable”. I’m wondering if what you want to say is something like “"I'll show you something someone like you will want to have."

I think the sentence is fine in a limited context. Say you go to a doctor with symptoms and he looks at some tests and isn't sure what the diagnosis is. So he says "I'll show you something you likely have." Then he refers you to a specialist. I'm not saying most docs would say this, but it's possible and it makes total sense in this situation. That's the only thing that comes to mind where you hear this. There could be others, but it would have see the sentence in context. A mechanic might say " I'll show you something that might be going on with your car." Then he proceeds to draw a diagram. That works too.

you will want to have with 100%

expected to have or expected to want?