I want to display the post in 2 columns on mobile with little bit of spacing

Hi there,

you're using a plugin for the post list - you should check with the Plugin Author as to how to change that.

If they are no help then try this CSS:

@media (max-width: 767px) {
    .wp-block-advgb-columns.advgb-columns-wrapper .advgb-columns-container .advgb-columns.mbl-layout-12x4>.advgb-column,
    .wp-block-advgb-columns.advgb-columns-wrapper .advgb-columns-container .advgb-columns.mbl-layout-12x6>.advgb-column {
        flex-grow: 0 !important;
        max-width: 48%;
        margin: 1%;
    }
}