I am slowly going blind,

I would like to buy a phone with a larger screen than you get with most on the market. I am used to a Samsung galaxy and would like to stay with what I am familiar with. I have been looking at the tab A8 but am not sure which I can use as a phone. I will need the larger screen for the larger font size. Some are much too large for me to carry comfortably. Any help would be so nice. I am afraid to just order the one recommended on line. Some do not let you use them as a phone and others want to to be connected to your cell phone. I don't want to have to carry both. I just want to keep it as simple as possible, this adjustment is going to be hard enough. Any info on sim cards, locked v unlocked?