Partizan

Sorry for double post but just tweaked and made a working filter for my case – to change size of input field fonts ->

add_filter( 'wc_stripe_upe_params', function ( $stripe_params ) {
    // Modify the appearance settings for Stripe UPE to adjust font size only
    $stripe_params['appearance'] = (object) [
        'rules' => (object) [
            '.Input' => (object) [
                'fontSize' => '16px' // Set the font size to 16px
            ]
        ]
    ];

    return $stripe_params;
} );

Good luck.

I have same problem as @alexanderzhel88. Can’t apply ‘fontSize’ .

@alexanderzhel88 found a solution maybe?

Best regards.