Device performance deteriorating rapidly, unknown issues.

For a very long time my iPhone 7+ has had issues with apps randomly crashing, the phone running slow, internet and cellular connection not working properly, etc. The rest of my family owns the same iPhone but they don’t encounter some of the issues that I do. Recently, what was a decently annoying problem with my iPhone disconnecting from 4G cellular data randomly and going to 1x became a consistent issue. It used to happen every 15 minutes or so and last only 10 seconds or so. But now my phone constantly has intermittent issues telling me I have no service, zero bars, or I’m running on 1x (which does nothing). I don’t know what could have caused this issue. I fear the possibility of malware but my understanding is that malware on an iPhone is a very slim possibility. I go to some websites without secure connections, I’ve accidentally clicked on questionable links, clicked on adds that modify the phone’s calendar, and I’ve downloaded files online. Can any of these things plant Malware in my device?