To make this more clear, we must understand the difference of a native coin such as ETH and a token such as USDC, USDT, etc.
There is no way to "freeze" ETH because the Ethereum network is a decentralized blockchain that is designed in such a way that only whoever has the private key can control the ethereum funds for that address.
However, tokens on the ethereum network are smart contracts. The specific code on each smart contract defines the functions that can be read from the smart contract and written to the smart contract.
You do not need to understand the details fully, but just know that in the case of USDT and USDC the smart contract contains blacklist functions as you can see here:
USDC smart contract functions
USDT smart contract functions
Using those blacklist functions the issuer of USDC and USDT can freeze any address from sending the token, and there are many addresses that have been blacklisted from USDC or USDT as you can see here.
This isn't to say that all tokens are like that, for example the decentralized stablecoin token DAI does not contain any such blacklist features.
To summarize and answer to OP: Aside from some tokens as mentioned above, there isn't a direct way that a government could freeze your coins. In all cases where any government has confiscated cryptocurrency, it has always been because they managed to get the private keys to those funds.