Unpopular opinion but unless there is a sign or store policy that says no more customers past ex time then too bad. You signed up to work in customer service expect people to rock up late. You have no idea if they work a zero hours contract or have an alternate work schedule that prevents them from shopping at particular hours during the week.
This is why I make the distinction between essential and nonessential shopping. If you’re rocking up to a grocery store ten minutes before close because that’s the only time you have to get food and browsing the seasonal decor fifteen minutes after close. Not to mention there’s a different behavior pattern between people who genuinely need to get something at a store and people who think they’re entitled to hold up the entire staff for however long they want.