Storing current date into a variable

I am trying to achieve something fairly simple, and despite spending the last couple of hours browsing this forum I have not found my answer. Maybe I can’t search properly.

Anyway, there you go:

I’m building a dashboard plugged on an API (there is no db connection) and I need to send the current date (and eventually also current_date - n_days) as a parameter to the API.

It is my understanding that I have to create a variable first. This is where I’m currently struggling, I’m selecting “Grafana” as datasource in the variable creation form and then, I have no idea what kind of query so set in order to get my current date.
I tried several queries such as “SELECT DATE()”, “CURDATE()” etc… but nothing seems to work.

Any hint would be much appreciated!