It's better to be the original size, not more than four feet at most, otherwise the brushwork will change. Preface to Lanting, known as "the best running script in the world", is a masterpiece in the history of China's calligraphy. The full text consists of 28 lines and 324 words, with a height of 24.5 cm and a width of 69.9 cm.
According to Shi Shuo Xin Yu, "Wang Xizhi's Preface to the Lanting Pavilion is made of cocoon paper and calligraphy, which has a strong charm and is peerless." So he used cocoon paper, which does not absorb water in handwriting, but does not melt.
Therefore, you can write on smooth and clean modern paper.