Will my assets be blocked from trading as soon as placing a bid?

It depends on the rule of each blockchain. For EVM chains, your assets won't be blocked by anyone while bidding. The amount that you have bid remains in your wallet and not be kept in any contracts. It will not be deducted until the end of the auction.

For non-EVM chains (Sei Network and Injective), your assets will be kept in the contract while bidding, so it will be deducted from your wallet. Once there is a higher bidder, you will receive the token back to your wallet. In case there is no higher bidder and you are the highest bidder through the time, the bid amount will be locked until auction expired. Once it's expired, you will win the auction and receive the NFT.