1. First of all, the leather itself is not flexible, so there is no way to make it bigger. If you just bought a leather coat and haven't bought it for a long time, you can go to the place where you bought the leather coat and exchange it for a bigger size.

2, when the weather is not too cold, you can also wear leather clothes directly, so that there are fewer clothes to wear inside and the position of your arms will not be too tight. Of course, you can also make yourself slimmer by fitness, which can solve the problem of tight cortical arms.