In Winter 22 release, Salesforce releases Dynamic Gauge Charts in Dashboard, even still beta. Before this, all segments (low, medium, high) values must be entered manually by editing the component. With Dynamic Gauge Charts, you just need to update a field and the segment target changed.
To use Dynamic Gauge Chart, you need to enable the feature from Reports and Dashboards Settings in the setup menu.
Footer: once you select "dynamic" mode, you cannot make use of the footer by entering any text, it will be locked and will show the description, for example, Sum of Amount (USD) compared to Target (Dynamic: Rec-1)
- Sum of Amount (USD) = the needle of gauge chart, which is the current value in the database
- Target = field name
- Dynamic = object name
- Rec-1 = record name