Plenty of methods I guess. It's kinda hard to give a tailor made approach without knowing your style and level.
As a southpaw, elbow always tucked in since my leading side is where the liver located. I realized very quick you can have an "iron chin" but nobody has an iron liver...
Good question, because once a clean liver shot lands, it’s too late. You have to prevent it from happening in the first place. If you’re orthodox: Keep your right elbow tight to your side, especially when inside. Don't let it flare when you punch. Pivot out to your left after combinations, standing square makes you a target. When slipping or rolling, don’t overcommit and expose your right side wide open. If you’re southpaw: Same idea, but reverse it, your liver is now more exposed when orthodox opponents throw straight rights or left hooks downstairs. Keep your left elbow tucked and use small steps back and right to take their angles away. For both stances, good footwork and tight defence matter way more than trying to "block" body shots last-second. Best way to defend the liver is controlling range and never letting your side sit exposed for free.
If you lower your elbows to block it, you risk being open for a head shot if they fake you out. If you keep your guard up high, they can sneak in the body shot under your elbows. What to do? Old skool fighters simply dipped their knees. That way, they could block the punch without having to lower their guard. And if it was a fake and they threw to the head, the punch would go over since you bent your knees and dipped. Kill two birds with one stone. Old skool fighters understood efficienct fighting.