Symmetrical full fibre is the product where upload matches download. It includes a free static IPv4 address.
The address is assigned after the circuit is live, not at checkout. The same number is not guaranteed if the service is later migrated or set up again.
Other broadband products use a dynamic address unless you ask for a static IP. Openreach full fibre plans are often asymmetric: the plan shows both speeds, such as 80/20 or 1000/115.