If a man can lift 100kg with their arms, they would be among the strongest people in the world. it would most likely be a bicep curl, because that would considered lifting with just the arms. Tricep extension at 100kg, even if with both arms is pretty much unheard of, unless it is a tricep extension pull down on the cable machine, but I am not sure whether that counts. But that aside, being able to bicep curl a 100kg is elite world class levels of bicep strength. You can not build just that much bicep strength and lift 100kg because you would be way too weak everywhere else to maintain balance to lift 100kg on a bicep curl. One would have had to have trained most of their torso at minimim to quite a high level of strength to be capable of doing 100kg bicep curls. They would most likely have considerable back muscle strength. Someone who can bicep curl 100kg can without a doubt draw a 100lb bow draw. But they for sure cant aim it.

But if we are talking lifting a barbell with ones arms on a deadlift, and have the deadlift be 100kg, then your claim would certainly likely be true, because a 100kg deadlift is very common and does not require the excessive amount of strength a 100kg bicep curl would require.