Which topology is best to design a DC DC 120W Power Supply? Kindly go through details
This may help to select topology based on power levels.


All the basic protections like short circuit, Reverse polarity.


Protection against input voltage with reverse polarity is independent of the converter's topology. You can build a simple reverse polarity protection with a MOSFET (ideally, PMOS) and a few passive components. However, if you want something like &quot;protection against applying voltage from output-side with even reverse polarity&quot; don't laugh, you can see such requirements in automotive then things may change.


No power consumption when no load.


There's no such thing as &quot;no power consumption at no-load&quot;. There should be some acceptable power levels. For example, EU 2019/1782 ANNEX II defines the maximum allowed power consumptions for different power output levels (including no-load). So you should explicitly specify the no-load power consumption.
Anyway, here are my thoughts:

LLC converters are a bit problematic at no-load regulation. So I'd not go for LLC. But if the controller has some magic inside for no-load regulation then LLC may be an option.

Flyback could be another option. But flybacks are terrible in terms of EMC performance. Though you didn't specify any EMC requirements so I don't want to say anything extra about this.

I'd go for either two-switch or active clamp forward converter.