Is it possible to create a smart contract, for example a ERC-20 from a multi signature smart contract wallet?
Sure, it is possible, but wallet contract has to support this. Normal transactions and smart contract creations are performed via different opcodes, and most implementations of multisig wallets just do not have opcodes for smart contracts creation, namely
CREATE2. ABDK Multisig Wallet is an example of multisig wallet with contract creation ability.