A new plain text simplified Chinese corpus CLUECorpus2020 was released this year; see the paper at the arXiv. It is extracted from Common Crawl between the dates of July to December 2019.
The files are downloadable from links from their Github page (which lead to Google or Baidu cloud services). They include 新闻语料 (news corpus) 8GB, 社区互动-语料 (social interaction corpus) 3GB, 维基百科-语料 (Wikipedia corpus) 1.1GB, 评论数据-语料 (comment data corpus) 2.3GB.
The other large corpus I'm aware of is the Leiden Weibo Corpus (download from here) which "consists of 5,103,566 messages posted on Sina Weibo in January 2012" (Weibo is sometimes considered the Chinese equivalent to Twitter). An example from this corpus is:
"3399658661888659","44","3","m","有建要学会快乐","啊~~~裸考...现在还来得及，全裸还是半裸？快点复习一下电脑才行呐...我不要跟师弟师妹一起上课[泪]不不不，好烦好烦[生病][生病][生病]","30","啊 裸考 现在 还 来 得 及 ， 全裸 还是 半裸 ？ 快点 复习 一下 电脑 才行呐 我 不 要 跟 师弟 师妹 一起 上课不不不 ， 好 烦 好 烦","啊/SP 裸考/NN 现在/NT 还/AD 来/VV 得/DER 及/VV ，/PU 全裸/AD 还是/AD 半裸/VV ？/PU 快点/NN 复习/VV 一下/AD 电脑/NN 才行呐/NN 我/PN 不/AD 要/VV 跟/P 师弟/NN 师妹/NN 一起/AD 上课不不不/VV ，/PU 好/AD 烦/VV 好/AD 烦/VV "
This not only includes the plaintext but also segmentation and POS tags and further information.