Hi Petar,
The first site is still using the old typography system. The new typography system, used by your second site, is better. You can refer to this article for more information regarding it: https://docs.generatepress.com/article/dynamic-typography-overview/
You should be able to set the typography set on your first site on the second one. Just add your font through the font manager and set a Typography rule for the body in the Typography manager.