Disciplining toddler

I was raised on spanking and I personally do not like it. I’m trying to find gentle ways to discipline and it’s getting harder to do. My LO has been pushing boundaries hard lately, doing things she knows she’s not supposed to, not listening, “talking” back and screaming at me when asked to do small things that used to be no fight. We do time outs when needed but now she enjoys her timeouts. If I tell her she’s going to time out she will walk over to where it is and say yes like she wants to do it. I’m about to have my second baby and everyone keeps warning me it’s about to get worse and I just need some advice.