I'm a layman myself, but here's my thoughts:

If you know where the target is going to be making the calls you want to listen in on, then bugging the room is quick and easy.

If that's not an option, then you might be able to force the target's phone to instead of 4G or 5G use 3G or even 2G, which are unsecure and can be easily listened in on. (provided you're at a reasonable distance when the call is being made). This is becoming harder and harder as more and more phones refuse to use these networks.

If by texts you mean SMS, then the second one applies to those too. If you mean using an app, then probably not. However, then it would be possible to gain access to their account, which ranges from easy to impossible.

I think other than that you would need full access to their phones by remotely infecting it or stealing it and uploading your spyware on it to achieve either.

In short I think a phone call might be more doable, or rather they're equally difficult.

I too call on the smarter people to correct me.