I need to have the client’s theme colors here so he doesn’t have to remember the color codes each time he’s using them.

Is
is there any way to Add/Remove/Change some colors from the default “Paragraph” block color settings side panel?
Thank you in advance!
Rather than adjusting the default palette, you can define (and enforce) a custom palette.
<?php
// Add a custom palette
add_action( 'after_setup_theme', 'wpse_block_color_palette' );
function wpse_block_color_palette() {
add_theme_support(
// Define the colors
'editor-color-palette', array(
// First color - black
array(
'name' => esc_html__( 'Black', 'textdomain' ),
'slug' => 'black',
'color' => '#2a2a2a',
),
// Second color - blue
array(
'name' => esc_html__( 'Blue', 'textdomain' ),
'slug' => 'blue',
'color' => '#0000ff',
)
// And so on and so forth
)
);
}
?>
You’ll then want to add styling for the classes they’ll generate. The palette applies to any block with core styling, which boils down to “has-(slug)-background-color” and “has-(slug)-color”.
.has-black-background-color {
background-color: #000;
}
.has-black-color {
color: #000;
}
.has-blue-background-color {
background-color: #00f;
}
.has-blue-color {
color: #00f;
}