Yes, it is possible, but I would always install RAM in pairs if possible, and it doesn't hurt to buy RAM that offers the maximum clock speed of 3200 MHz.
If you haven't bought the NUC yet, I would advise against it, because the 10th Gen Intel CPUs are not exactly famous for being particularly fast. If the purchase is still pending, I would rather choose this one:
Intel WALL STREET CANYON NUC12WSKV5 (Intel Core i5-1250P)Here is a processor comparison with an Intel 12th Gen 1250P, the new one is 3 x as fast.
https://www.cpubenchmark.net/compare...