Foreshadowing is a big part of Bridgerton, as is the use of colour in the costumes, and season 2 was no different. Whilst the colours of the costumes in season 1 tracked the journey of the leads, specifically Daphne, in season 2 the colours were used to show that Kate and Anthony were meant to be, but in episode 4 colour was used to foreshadow two specific Bridgerton Brides.
Kate:
In the beginning of episode 4 we see Kate in a light 'Bridgerton Blue' dress, the colour and the pattern matches Anthony's waistcoat. Whilst the matching colours through the season indicated it was Kate that Anthony was destined to be with, it is this dress in Bridgerton Blue that points to Kate becoming a Bridgerton. Kate wears this lighter blue only twice in the season, the first time is at the first ball when she first overhears Anthony, and again at the beginning of the House Party at Aubrey Hall. I believe that this is the most significant moment of her wearing the signature Bridgerton Blue. Kate is wearing the family colour at the country estate of the family she will soon be the head of, and it is significant that she is wearing this colour at the beginning of the house party.
Penelope:
Penelope is known for wearing yellow, however, in season 1 we had seen her in some pink and a bright lime green, in season 2 she is generally back in yellow, however, in episode 4 we see Penelope in green, and not the garish lime green we have seen her in before, but a softer green colour. This is significant on two points, first it points to Penelope being a future Bridgerton Bride, with her dress colour being a mix of the yellow she would normally wear and the Bridgerton Blue, secondly this was a deliberate choice by the costume designer to put Penelope in Green at this point in the show as an easter egg for season 3, it is at the Bridgerton country estate, and marks the beginning of the house party. It is also significant that in this scene Penelope is with both Colin and Eloise - who are both in Bridgerton Blue.
What we see in episode 4 is two Bridgerton Brides, the one whose season it is and the one for the next season, in colours that represent their future within the Bridgerton Family. Kate as the future Viscountess wearing the family's colour, and Penelope as the future bride of the third son in a mix of her family colour with the Bridgerton family colour.
I look forward to seeing the colour journey in season 3 as we watch Penelope and Colin's relationship develop, and as we watch for the next Bridgerton spouse.