by "central bank" I'm frequently referring to the broader set of the legal framework behind the macro monetary policy

in most countries central banks plays a key role, but they frequently co-exist in a larger network of institutions

so it may not only be central bank setting the rates and affecting liquidity

for example, when US Treasury auctions bonds, they're both, temporarily reducing the effective amount of USD in circulation and providing more high-quanlity collateral

this collateral (US Treasury bonds) can then be used on wholesale debt markets to issue more credit

moreover, this collateral can be leveraged/rehypothecated, thus increasing liquidity

still, in the USA the Fed continues to dominate in importance

in Russia, besides the Bank of Russia there's also the National Wealth Fund (NWF), which is operated by the Ministry of Finance

in China, there's policy banks, such as China Development Bank which are supported by PBoC's facilities