If you are asking how to "code" the changes it is possible to make interactively via the Settings --> Configuration Menus, something like this is probably what you want:

settings = {}

# general settings - companies - document layout
settings.update({"external_report_layout_id": env.ref('web.external_layout_boxed').id})

# accounting settings - taxes - default taxes
settings.update({"sale_tax_id": False,"purchase_tax_id": False})

# accounting settings - analytics - analytic accounting
settings.update({"group_analytic_accounting": True})

# apply changes
self.env['res.config.settings'].create(settings).execute()

Each App has a series of fields on the res.config.settings model that enable features and store configuration options, for the Accounting App you can see many of them here:

https://github.com/odoo/odoo/blob/18.0/addons/account/models/res_config_settings.py

You can also update records:

company = env.ref('base.main_company')
company.update({'name': 'ACME USA Inc.', 'street': '100 Main Street', 
                'city': 'Springfield', 'state_id': self.env.ref('base.state_us_5').id, 
                'zip': '90123'})

Activate currencies:

self.env.ref('base.AUD').update({'active': True,'symbol': '$AUD'})

Install Apps:

for app in ['stock','contacts','helpdesk','sale_purchase','sale_management','crm','web_studio']:
    self.env['ir.module.module'].search([('name','=',app)],limit=1).button_immediate_install()

Change which view is the default for a Window Action (we don't want the Kanban view by default when looking at Contacts)

self.env['ir.actions.act_window.view'].search([('view_id','=',self.env.ref('base.res_partner_kanban_view').id)]).update({'sequence':5})

Hi,

Please refer the following documentation:

https://www.odoo.com/documentation/18.0/administration/odoo_sh.html

Hope it helps