By default, Odoo aligns numeric fields to the right in both the header and body of tree views. To left-align a specific field, you can patch the ListRenderer and adjust the DOM once it's mounted.

Here’s how I solved it using JavaScript in Odoo 16+ (OWL architecture):

/** @odoo-module **/
import { patch } from "@web/core/utils/patch";
import { ListRenderer } from "@web/views/list/list_renderer";
import { onMounted } from "@odoo/owl";
patch(ListRenderer.prototype, "align_left_area_size", {
    setup() {
        this._super(...arguments);

        onMounted(() => {
            const headers = document.querySelectorAll('div[name="one2many_ids"] th[data-name="integer_field"]');
            const cells = document.querySelectorAll('div[name="one2many_ids"] td[name="integer_field"]');

            headers.forEach((el) => {
                el.classList.remove("text-end");
                el.style.textAlign = "left";
                const labelSpan = el.querySelector("span.text-end");
                if (labelSpan) {
                    labelSpan.classList.remove("text-end");
                    labelSpan.style.textAlign = "left";
                }
            });
            cells.forEach((el) => {
                el.style.textAlign = "left";
            });

            document.querySelectorAll('div[name="one2many_ids"] th[data-name="integer_field"] div.d-flex').forEach((div) => {
                div.classList.remove("text-end", "flex-row-reverse");
            });
        });
    },
});

This works for fields in nested One2many lists too, and you can adapt the selector for any other field. (I invite you to inspect the elements on your navigator to local better your field) 

Don't forget to add your file in the assets of your module's manifest.

I hope this helps!

Hi

Try this inside a css file 

th.o_column_sortable[data-name="field_name"]

{

text-align: center;

}

Hope it helps

Hi BB,

Try class="text-left",




Hope it helps.
Kiran K