Hello,

Please add this code to the Theme Settings > Custom CSS > Global:

body .widget_price_filter .price_slider_amount .button {
    font-size: 12px;
    color:#000000;
    border:2px solid #000000;
    background-color: transparent;
}

You can change the font by means of the Advanced typography option, which allows you to choose the item from a drop-down or insert your custom CSS class. Please navigate to the Theme Settings > Typography > Advanced Typography.

Here is the documentation providing more detailed instructions: https://xtemos.com/docs/woodmart/advanced-typography-settings/

The price label selector is:

.widget_price_filter .price_slider_amount .price_label

The prices range:
.widget_price_filter .price_slider_amount .price_label>span

Best Regards