LTE antennas for a smartwatch can be a notoriously difficult design and in most cases its unlikely a standard antenna will. This is usually down to the very confined space and other parts of the watch that are not antenna friendly like the display, casing and battery.
You the need to take in to account other issues surrounding performance. Firstly not all antennas work well when mounted close to the human body as they de-tune very quickly. Antenova has an antenna technology called MDA that is best suited for body warn products. Secondly it will depend on what LTE bands you need to support and what countries the product will be sold in. If you need support for sub GHz frequencies, then there needs to be sufficient ground plane length on your PCB which often is not the case in a watch. Then if you plan to sell your product in America, you will need to pass PTCRB and net work approval.
If would be good to discuss your architecture, LTE band requirements and countries to be deployed in for us to have a better understanding and to provide you with a more detailed and accurate analysis. Please go to the contact section of our web site to find more details.