I would suggest the following:
- You already follow the 20%-80% rule :) Perfecto!
- Review your Background Apps setting (I recommend disable all and only enable one's that are needed!)
- Review your battery usage in the settings to find out what is draining your battery as it doesn't seem normal imo. ' I just use Instagram for 15 minutes and it’s already down ~10%.'
- Use a slow charger when possible to reduce the temperature of the battery when charging!
- Keep your screen's brightness as low as possible will help but is a bit overkill. just don't use max brightness all the time lol
I know some of these are over the top but they will help over time!
Safe travels to your next destination :)
EDIT: Here's a short video which runs through settings which can help with prolonging an iPhone's battery life :)
No worries man!