Did the Royal Navy simply copy Brazil's River-class form for its Batch 2 ships?
Short answerNo; similar needs produced similar shapes, while the internal systems and arrangements determine the ships' real differences.
NotesThe Royal Navy's Batch 2 River-class ships and Brazilian relatives can look similar because they answer related seakeeping and carrying requirements. The external silhouette is not the defining measure of combat capability. Sensors, machinery, internal subdivision, communications, and mission systems account for much of the difference in cost and use. Modern hull shaping increasingly converges around common operating needs even when the spaces inside are very different. A shared profile does not make two warships equivalent.