As others have already pointed out, map size is probably not decisive in creating this intangible "feeling of adventure". Isn't it rather just a matter of how the regions of a game world are characterized by their writing and content? The "feeling of aventure" probably arises, more than anything else, from venturing out into the Unknown, travelling beyond the frontier of civilization. If everywhere I go the landscape is dotted with towns, inns, and shops, no matter the size of the world, it will lack in this regard. A fairly confined world map with a good contrast between "civilized" and "untamed" regions, however, may do the trick.
I feel that this may be easier to pull off in an open world map, because the hub structure always implies that you were meant by the designer to be at this specific location to progress this plot, while open world maps allow for a contrast between regions of low and high density content, which is a little more in line with the feeling of travelling the Unknown. But a good mixture of hubs - some plot-relevant, some only for sidequests or for open exploration, may instill the same sensation, whille an open map with too little heterogeneity in its content will fail.
To give some examples: Morrowind featured a fairly small landmass by today's standards, but the Ashlands and especially the area within the Ghost Fence were properly characterized as dangerous, untamed wilderness, compared to the settlements closer to the coast. Sense of adventure: Check! Ultima had major population centers and a well-maintained road network. But venturing to the Isle of the Avatar or into the Stygian Abyss, or even just a little away from the main roads? Sense of Adventure: Check! Witcher 3: Now, this may be highly subjective, but to me, this "sense of adventure" felt more tangible on Undvik, being abandoned with no current settlements, than almost anywhere else. Even though the island is, by area alone, tiny in comparison to the rest of the game world. Check!
Oblivion and its ilk provide the counter-example. Open maps, sure, but points of interest, including towns, are sprinkled so liberally over the map that it feels like a theme park. In a similar vein, space games that only ever let me approach planets via spaceports and space stations, rather than choose to touch down on an unexplored world's surface, completely fail to instill that feeling of adventure in me, despite offering what would, in terms of numbers alone, the vastest game world you could ask for.