I assume this was texts via the Samsung Messaging app.
Unfortunately unless you use something like the Goodlock App or a 3rd party launcher such as Nova Prime to change the colours it's going to be the green bubble because as far as I can see there are no native settings within the phone's menu systems to change the colours.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.