Hiring is like toilet paper. Most managers only think about it when they are out and in desperate need. This means showing up unannounced with your resume expecting respect and consideration probably won’t happen.
There are exceptions. My son is looking for a dish washing job. Dropping into a restaurant and shaking hands with the owner or manager can work. He made a strong enough impression that they gave him a couple of trial shifts last weekend.
He was smart about his timing. He did not ask to speak with the manager in the middle of a busy dinner service. No, he stopped by on a weekday between lunch and dinner when the manager not only had time to talk with him but was also in a thinking ahead frame of mind rather than the reactionary chaos of the lunch rush.
There are not many other roles that get filled this way. You cannot drop by a plant and expect to get a meeting with the Production Manager nor can you expect to have a meaningful conversation with the Marketing Manager of a non-profit on a drop by.
a) busy with more pressing issues (like the toilet paper order) or
b) just not in the right frame of mind to consider whether you would be a fit.
The bottom line is to be sensitive to your audience. Once you can identify who you need to connect with and the best way to do it, the rest will become clear.