Have you checked the health of your battery? Go to Settings, scroll to Battery, click it, then click Battery Health. ALSO note the battery usage for apps on that first page under Battery, it will tell you which apps are using the most battery, AND which use background activity. Consider getting rid of offenders, IF you can live without the app.
Some social media apps can be a culprit, many use background activity. In most cases you CAN access the social media platform via the web, this works well for FaceBook for example, so maybe you CAN live without it and just check in via the FaceBook mobile page, or whatever platform's mobile website.
PS IF your battery health is bad say below 50% then you may want to get Apple to replace it. They have an ongoing deal on that for 29 dollars.