Last tested: Oct 19, 2020
Only for Embed dashboards.
For Dashboards-Next, it is one of the settings under Dashboard Page in Custom Themes (note that this is a license feature, so it will need to be enabled on an instance).
For regular dashboards, there is an "embed settings" option that lets you edit certain options for an embedded dashboard. There are LookML dashboard parameters too.
The options look like this:
You can't do this for dashboards in the Looker UI.