I applied CSS and js in odoo14 below it is completely worked:
template id="assets_frontend" inherit_id="website.assets_frontend" name="Custom Assets">
xpath expr="//link[last()]" position="inside">
link rel="stylesheet" type="text/css" href="/custom_module/static/src/css/style.css" />
/xpath>
xpath expr="//script[last()]" position="after">
script type="text/javascript" src="/custom_module/static/src/js/test.js" />
/xpath>
/template>

when I applied in odoo16 in the manifest below but it is not worked:
'assets': {
'web.assets_frontend': [
'custom_module/static/src/css/style.css',
'custom_module/static/src/js/test.js',
],
},