Hi Basteve54. Your boosted relics are the ones for factories that will always produce more for you, once the production boost is unlocked. There are a few ways to tell what they are (or will be). Your boosted provinces are located on your map at 12 o'clock, 5 o'clock and 7 o'clock, around your city.
The factory, once you build it, will have a green arrow next to the amount, as will the good, in the trader menu. On browser, or mobile, in page 2 of the Main Hall menu it will be outlined in a different colour from the rest.
In the research tree, it will listed behind the original three, as a 'boost'.
On mobile app, the number of boosted relics appears as a shortcut, on the World map menu, in the top left corner.