If you want to make sure you always see posts from particular accounts you follow, go to their profile and click the notification bell:
➡️ fedi.tips/how-to-be-notified-w…
The official apps don't yet have this feature, but third party apps do and so does your server's website.
If you want the official apps to have this too, and if you're comfortable using Github, you can give a thumbs up at:
Android
github.com/mastodon/mastodon-a…
iPhone/iPad
github.com/mastodon/mastodon-i…
How to be notified when your favourite accounts post on Mastodon | Fedi.Tips – An Unofficial Guide to Mastodon and the Fediverse
An unofficial guide to using Mastodon and the Fediversefedi.tips