How can i make food have a more desirable smell?

In general, cold and room temperature food need more seasonning as the volatile compounds that make up odor (what you smell) will not be as, erm, volatile.

There is not set rule on how much to add; experience plays a big role here.

When cooking your ingredients, in your case, chicken, you can add a little bit more seasoning, herbs, spices, salt.

Just be careful not to add too much as some herbs and spices can become bitter in larger quantity.

For your specific case, I would add cilantro and lime to the wraps.

(In my taste, ) I would skip the carrots and cucumber as they are not that flavorful and add water to the end product; make a side salad with them.

Your ingredients look ok. I am suspicious that you are not cooking at all; the chicken is already cooked. You are assembling ingredients. Good lunch making - I do it all the time.

You have an idea of how a wrap should smell because you have eaten ones that have a smell you like.

A way to accomplish that in a predictable way is sauce. There are seasoned sauces of all sorts that have great smells. Get a wrap you like and see if you can figure out what the sauce is that makes it smell good, then buy some and use it. Toss your ingredients in the sauce so they get saucy then assemble.