I think you are going to run into my issue https://community.grafana.com/t/prometheus-query-step-alignment-issue/17826 but if you live in GMT or want daily max on that clock you would put something like this into your line or bar chart:
max_over_time(yourGaugeMetric[1d])
Specify ‘1d’ as your step time. Set the range of the dashboard to whatever 30 day period you are interested in.