Bad kid

So I know it’s my fault but I have a bad 2 year old omg I probably should of disciplined her sooner but I had a lot on my plate and it was always easier giving in but I’m at a point where I’m fed up! How can I make discipline a part of our routine? My kid is awful she won’t take no for an answer, she can be mean to her siblings. Whatever she wants she gets! I know it’s my fault for giving in but I’m determined to change our ways. I also have a great 8 year old she’s amazing and a 4 month baby. We all share meals together but she will eat all day if she could and if I say no she throws a fit idk what to do I even put a safety kid lock on my fridge (I think that’s crazy I never thought I would have to do that, if I wouldn’t lock it she will take out our veggies bite every single one take out butter, milk jug just make a mess), she takes her clothes off at home even when I say no it’s like if I’m not speaking. When we go to church she wants to take her shoes off and I have to hold her down till she finally forgets she will run around and I have to hold her I even spanked her bottom buts it’s like nothing to her! She is very sweet and smart I love her dearly but I’m running out of options the only thing me and my husband thought of doing was time out and see how it goes! We don’t spank our kids, I did recently just to see but it didn’t make a difference to her, So were not even doing that to her, I may sound naive or dumb I’m not I always thought my kids would be good since my first was an angel but this little girl is different and it’s so tiring lol I love her and love motherhood but I just can’t !! Please leave suggestions nothing rude! We’re definitely trying our best!