I struggle with the same problem, though I've got much better at at it. I think it's a mix of my own personal insecurities, and the lack of consistency amongst policies and leadership. Every guest situation is different and unique. Once I got comfortable in my work center, I got a lot better in standing my ground. I now only have to ask for help if the guest insists on speaking to a manager. Unfortunately, I'm not intimidating enough, or at least I don't get taken as seriously I guess. I cringe every time I have to bother an LOD or GSTL just because the guest won't accept an answer from me.
I guess my best advice would be to simply tell leadership about your concerns with how to handle guest conflicts. I wouldn't call it "conflicts" though, because I don't think your leadership would like you calling guest interactions as "conflicts." I would just try and get the point across of "how much authority do I have" so you don't have to call leadership as much. Hopefully they'll work with you. In the past I've just been told to "say yes to everything." That did not please me, it's so dismissive. Lol.
Also, I would just get as well informed about policies as you can, so guests don't argue you into a corner. The more confidence you have, the easier it is to honor said policies.
