Hi,

In Odoo 16, the line_ids field on the account.move model (used for invoices, bills, etc.) is a One2many relation to the account.move.line model. The field responsible for computing tax-related values, including tax_base_amount, is handled mainly in the accounting and tax engine, and is triggered during the creation or modification of invoice lines and taxes.

line_ids is defined like this in account.move:

Hope it helps