Good day my bro! Greetings from Chile. The truth is that distance is always related to the amount of W and the amount of PPFD; this figure measures the number of photons the plant receives in a specific growing area, and this increases as the plant grows..
Seeds germinating and seedlings: 200 to 400 PPFD
In growth: 400 to 600 PPFD
In flowering: 600 to 1000 PPFD
I calculate about 40cm to 60cm as a minimum; if it's with power regulation, you can get as close as about 20cm approx. It all depends on the brand and what lights your LED is.... greetings my brother! Total success!