Simple C++ code I adapted from Will McGugan's snippet (@ https://github.com/Textualize/rich-cli/blob/0721cb196661687d8ecd9af4baf48576b240c978/src/rich_cli/__main__.py#L145-L160)

gradient_text.cpp

#include <iostream>
#include <string>

struct color {
    short r;
    short g;
    short b;
};

std::string as_24bit_ansi(color values) {
    return std::string("\x1b[38;2;")
           + std::to_string(values.r) + ";"
           + std::to_string(values.g) + ";"
           + std::to_string(values.b) + "m";
}

/*
* Adapted from Will McGugan's snippet at:
* https://github.com/Textualize/rich-cli/blob/0721cb196661687d8ecd9af4baf48576b240c978/src/rich_cli/__main__.py#L145-L160
*/
std::string add_gradient(std::string text, color first_color, color second_color) {
    short diff_r = second_color.r - first_color.r;
    short diff_g = second_color.g - first_color.g;
    short diff_b = second_color.b - first_color.b;

    std::string colorized;
    for (int c = 0; c < (int) text.size(); c++) {
        double gradient_factor = double(c) / double(text.size());

        color actual_colors = {
            short(first_color.r + diff_r * gradient_factor),
            short(first_color.g + diff_g * gradient_factor),
            short(first_color.b + diff_b * gradient_factor)
        };

        std::string ansi_sequence = as_24bit_ansi(actual_colors);
        colorized += ansi_sequence;
        colorized += text.at(c);
    }

    colorized += "\x1b[0m";
    return colorized;
}

int main() {
    std::string sentence = "Lorem Ipsum Dolor Sit Amet.";

    color color_1{255, 0, 0};
    color color_2{0, 235, 255};

    std::cout << add_gradient(sentence, color_1, color_2) << '\n';
    return 0;
}