@nullius see Bulletproofs: Short Proofs for Confidential Transactions and More I didn't check the link posted by @ETFbitcoin but it's surely about the same. As for the quote, I didn't bookmark the link so not sure from where I got it :/ (edit; I got it from the PDF itself lol)
I think Monero is using Bulletproofs or planned to.
But i don't see any discussion mention which says it can reduce blocksize since it's bigger than normal signature size even though it's far smaller than CT signature size.
Edit;
Bulletproofs are designed to enable efficient confidential tranactions in Bitcoin and other cryptocurrencies. Confidential transactions hide the amount that is transfered in the transaction. Every confidential transaction contains a cryptographic proof that the transaction is valid. Bulletproofs shrink the size of the cryptographic proof from over 10kB to less than 1kB. Moreover, bulletproofs support proof aggregation, so that proving that m transaction values are valid adds only O(log(m)) additional elements to the size of a single proof. If all Bitcoin transactions were confidential and used Bulletproofs, then the total size of the blockchain would be only 17 GB, compared to 160 GB with the currently used proofs.