MacBook Pro 15 inch mid 2012 hardware help

Hello guys, I would really appreciate help in regarding am upgrading my MacBook Pro 15’ mid(2012) The upgrade consist of the following: - 16 GB RAM DDR3 - 1TD SSD My MacBook already came with a graphic card Here is my question and I hope someone gives me a positive answer and what is the best to do. Can I install for example Mac OS Sonoma straight from the Apple Store or I have the DMG file? I really don’t want to do it through the application open patcher I am well aware that it’s not compatible. the max I can upgrade is Maverick or Big Sur. Please guys who knows or done this before give me his experience and I would appreciate it with like or not like so I know fina solution. I hope this is the right page to ask this type of question if not please direct me I’m sorry I’m posting it on two pages, but I don’t know which one is the one that would help me more