Hair help please lol

So I haven’t dyed my hair in over a year and haven’t been to a hair salon in 10 years (had a horrible experience) I was just wondering if any of you have use this bleach color from L’Oréal and if you had good results? This is my hair right now

I’d like the top of my hair to match the rest of my blonde, It’s sitting at a level 8-9 I think. I want it at a 10. the hair color stuff I’m talking about is this. I’m just nervous that the top will be lighter then the rest.

Or should I do my whole head? I have a lot of hair so I’m unsure lol. Thanks for any feedback!