It's pretty easy to say 'no, I will not connect my personal phone to the corporate network in exchange for allowing my employer to remotely manage my personal phone'.
Get a second company phone like anyone with a sliver of opsec intelligence does.
No, I'd rather blame the world for my ignorance and expect them to pick up the tab on that bill. /s
Many years ago ago, at my first tech job, the employer provided a smart phone as part of work/on call responsibilities. (This was still around the era when smart phones were just blossoming as useful devices). Every other employee there decided to use their company phone as both their personal and professional device, while I opted out for what are very obvious reasons. I had my phone and I had the company phone; the latter was only on my person when professionally necessary.
It was common sense then, and it's common sense now. You always keep professional and personal assets separate.
(Fun fact worth noting: not too long ago the company decided to either boot personal usage of company devices, or stop providing those phones altogether. Can't say that I didn't warn them.)