I think it's you that needs to adjust.
My daughter's "big" school had the y6'slearning how to manage phones ready for y7.
Get her a phone. if you're THAT worried get a contract with something like the EE Safer SIM. I'm an IT person. We all have higher end Samsung phones, and my daughter has Google parent settings on her mobile and Microsoft family on her laptop for time management and app knowledge. And Life360 for safety when walking to and from school, and when she goes into town on her own by bus (they do tend to start doing this by end of y7. She going to change and go up quick be prepared for it.
The kids message mostly by WhatsApp and Snapchat. She won't have Snapchat and Tiktok until I'm happy I can get the settings for her safety just right. But I did what we do with clueless adults in I.T. I taught her safety, awareness and what to do IF. It's 100 times safer than saying you can't and they do stuff unsafely behind your back. My daughter also knows until 18 I have the right to do mobile safety check on messages, photos etc.
TBH her quickest route to bullying at high school. Your language and handling. It's big school when they go to school at 5 from nursery. She's 11 and going to high school. She's going to hang out with friends not have play dates. Play dates stop about 7 years old.
You need to adjust to be the mum of a teenager now. Be there, supportive, listening ear, safety rules (not over the top), the occasional nag. but the key phrase is I can help if you need it, but it's ultimately your responsibility. This applies to homework, having things ready, knowing about things like letters for trips etc etc. Most high schools now have parent apps for info like homework, topping up food credit etc etc. If not she needs to manage what she wants re packed lunch vs canteen food. Give her budgets, get her equipment. Spending money for any local shop is useful. It a normal part of walking hone with friends if you have a shop that lets the high school kids in it straight after school. Then just let know your there if she needs advice. but she needs to manage herself. Let her walk to school orzdrop her nearby but please don't ve the mum shouting love you at the school gate. And these friends you've introduced her to. They could just as easily be in different forms, different lesson, different sets, different breaks etc depending on how the high school is. It's honestly best to leave friend making to them.