Everything said up to now is all good info. I've had birds with crop issues, and my experience is pretty much the same. The only backed up crops that I've been able to resolve have been caused by parasite loads, and were able to clear once the parasites were taken care of. Those caused by reproductive issues (which is a common cause) don't really get better. I have had a few birds that developed pendulous crop and was able to keep them going with a crop bra. If the crop gets stretched out for some reason, genetics, a piggy eater, or a transient problem that resolves, then it generally does not go back to normal and will not empty properly. A crop bra can help. The only way to know is to try it. It may take several days to a week to see any improvement, if you are going to get any. When putting one on it can take some trial and error, and many adjustments to get it right, and usually you have to put it on looser at first, so as to not force contents up, and as the crop goes down, you can slowly bring it tighter to maintain a more normal crop size. See post #9 here for some more explanation:
https://www.backyardchickens.com/threads/blocked-crop.1484926/#post-24762420
Below is a picture of one of my hens that lived for about 2 years with a crop bra due to pendulous crop. Inked to show where it's tied, you can also see the ends of the ties sticking up on her back wrapped in black co wrap, to keep her and others from picking at them. The bottom of the bra should be comfortably snug against the keel so that they can't get their feet or legs caught in it, leave the top looser until the crop goes down some. Some birds tolerate it pretty well, some don't, and there can be an adjustment period where they may act abnormal while they get used to it. Keep an eye on her until that passes or it could possibly draw attacks from flockmates. Once it's been accepted and she's used to it, then it really passes without notice.
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