Historical data usage on Android Pie
I use this apps to monitor my data usage I found it useful. You should try if you want.

https://play.google.com/store/apps/details?id=com.internet.speed.meter.lite&amp;hl=en&amp;referrer=utm_source%3Dgoogle%26utm_medium%3Dorganic%26utm_term%3Dinternet+monitor+android&amp;pcampaignid=APPU_1_6egZXfunKIv6wAP8_ovoCA

https://play.google.com/store/apps/details?id=com.glasswire.android&amp;hl=en&amp;referrer=utm_source%3Dgoogle%26utm_medium%3Dorganic%26utm_term%3Dglasswire&amp;pcampaignid=APPU_1_segZXchYxdb5BvHunLAF