Thank you for your answer?I experiment with the Governance Module where the arguments can be number and string in JS. It is this Part of the Action struct: "pub arguments: ManagedVec>" I would like to avoid the Explicit way. Is that possible? Could the ErdJs detect that it is a Number and convert it to Bytes correctly?

It is (somehow) possible to convert a number to a buffer (big-endian or little-endian) - using standard Buffer functionality (no erdjs involved). After that, you should be able to use the buffer as an argument to your function (without the explicit format). For example: https://nodejs.org/api/buffer.html#bufreadint32leoffset erdjs is not able to convert from number to bytes, at this point: https://github.com/ElrondNetwork/elrond-sdk-erdjs/blob/main/src/smartcontracts/nativeSerializer.ts#L209