...locked down, locked up. Locked horns; lock jaw; lock gate; lock, stock, and barrel (there is a strange phenomenon, called 'semantic satiation', where repeating a word over and over makes it seem to lose its meaning).
In A Room of One's Own, Virginia Woolf thinks how unpleasant it is to be locked out; but it is worse, perhaps, to be locked in. We have all been, to a greater or lesser extent depending on our situation, locked in. But also, locked out. Locked out of others' homes, locked out of social spaces like cafés, play areas, and more.
You could write a response to Woolf's pondering, based on your recent experiences. Is she right, is it worse to be locked in? Or, if you prefer, play with the word lock, its different uses in compound words or phrases, the sounds it makes when repeated or in combination with other words, and see where that takes your writing.
