The change log for Rest API 2020-10 https://shopify.dev/changelog/removing-the-ability-to-change-the-tax-field-data says:
Was this functionality moved to another API, is there any replacement to change tax field data?
Shop.json API returns some tax settings that we can use (i.e. whether price includes tax).
Countries.json API returns country/tax values. But I see zeros for EU countries. For Rest-Of-The-World countries, yes, I see the values entered on Tax Settings page. As per changing Tax value it's readonly via that API due to "As of version 2020-10, the tax field is deprecated."
Could you please clarify how the following can be done via API:
1) Getting tax values for EU countries
2) Setting tax values for EU and Non-EU countries
3) Getting/Setting Tax overrides