It will make no difference who wins the franchise as the requirements for the service will be laid out by the government including a service requirement through different parts of the day and night. The bid will to be to meet the level of service laid down.
For Thameslink there were 392 pages of requirements which was found by googling thameslink franchise document. (Thameslink, Southern and Great Northern franchise train service requirements). The agreement came to 662 pages. (Govia Thameslink franchise agreement: execution version)
https://www.gov.uk/government/public...via-thameslink
I can't find one for East Anglia so I don't think it has been made public.