Ofcom has already been in close contact with social networking services and Dame Melanie said when the new legal safeguards became enforceable the regulator would be “ready to go”.
She added: “We know that some of them are preparing but we are expecting very significant changes.”
Dame Melanie said changes could also include allowing people to take themselves out of group chats, without anyone else being able to see they had left.
The Online Safety Act aims to force tech firms to take more responsibility for the content on their platforms.
Ofcom has the power to fine companies which break the rules up to 10% of their global revenue. It can also block access to their businesses in the UK.
Dr Lucie Moore is the chief executive of Cease, the Centre to End All Sexual Exploitation. She welcomed Dame Melanie’s comments about putting the onus of keeping children safe on the tech companies.
However, she was disappointed by “the lack of clear definition in the plans that Ofcom has drawn up to regulate online harms”, specifically on age verification methods regarding pornographic material.