Basic Trope: A weapon is carried or brandished when not appropriate.
Alice walks into a bank, a courthouse, a church, or a similar location where weapons are either forbidden by law or at least considered threatening and unwelcome, openly carrying a gun, sword, or similarly obviously lethal weapon.
Alice is carrying not just one gun, but several guns, a fully loaded bazooka or rocket launcher, belts and canisters of ammunition, grenades, and looks like she just walked out of Rambo as she walks into the place.
Alice drives a fully loaded armored personnel carrier or tank up to the drive-in window.
Alice's weapon is a Joke Weapon such as a fish or SuperSoaker.
Alice's weapon is, while a weapon, a small pen knife or nail file or can of pepper spray, and it's only taken out when she's checked for weapons.
Alice is an active-duty soldier and cannot keep the weapons/armor elsewhere.
Alice is a police officer or employed in law enforcement AND actively pursuing a dangerous suspect.
The setting is one that allows for carrying weapons everywhere.
Alice is filming a scene for a movie and walks into the nearby coffee shop on break, having put orange tape on the "weapons" she still wears to make sure no one mistakes her for an actual threat.
Alice is entirely unarmed (possibly even to the degree of being naked) in an active combat zone or similar situation where one would expect someone to be (possibly heavily) armed.
The location is a live fire range for elite target shooters, and Alice has brought a Super Soaker squirt gun.
Subverted: Alice is carrying a weapon into a place where it is not appropriate, but it is concealed and she has a concealed carry license.
Double Subverted: To everyone in earshot, Alice then immediately starts bragging that she has a 357 Magnum strapped to her side.
Parodied: Alice walks into a peace conference at the United Nations...armed to the teeth as in Exaggerated and carrying the Russian nuclear football she wrestled from Vladimir Putin.
Zig Zagged: Alice is a police officer but has her gun holstered and the safety on when she stops into the bank. Someone announces their intent to commit a Bank Robbery, and she unholsters the gun and points it at the bank robber while arresting him.
A society or setting where weapons do not exist, or are unavailable to anyone outside the military, and the military is not allowed to carry them on home turf outside of active war.
A Fantasy setting where everyone is a Squishy Wizard and physical combat arms aside from perhaps wands do not exist.
Real Life: Carrying guns or other weapons into many places will get one arrested at best or killed at worst.
Alice walks into the bank or courthouse or church or wherever with her openly carried gun, and is arrested, shot, or both - or at the very least, told to Get Out and never return.
The setting is Real Life or Like Reality Unless Noted, but it is also a small town that pretty much only revives in hunting season and does business with hunters. As long as the person is known and their weapons are obvious hunting gear, they're likely given a pass for most places.
The setting is Real Life or Like Reality Unless Noted, but it is close to a military base or active combat zone. As long as the armed people are soldiers and not fighting there, their weapons are ignored.