Some chicks have swollen abdomen just after hatching from where they have absorbed the yolk sac during hatching. My advice would be observe the navel area for signs mushy chick disease but from looking at your pic it dosnt look like that just keep an eye on it. Here's a link for you to check out so you know what signs to look for. Good luck with your chick.https://www.backyardchickens.com/a/mushy-chick-disease-yolk-sack-infection-omphalitis
You could try giving a dose of that. And clean the umbilical area with something anti septic.
It won't hurt to try. Personally I'd mix the antibiotic a little stronger than is recommended I've done it before for bacterial infection but never with a chick... Best of luck