Higher resolution is not a good choice for a permanent default because you lose the benefit of the larger screen.
Instead, go to Settings > Accessibility > Zoom
If you are using a trackpad, choose "Use scroll gesture with modifier keys …" This enables you to use the two finger swipe to enlarge the entire screen, including menus. Make sure to adjust how you want the window to move so you can see what is off-screen using "More Options" - I prefer "only when the pointer reaches an edge" to ensure a smooth, slow scroll sideways or up/down, but there are other choices.
If you don't have a trackpad, you can also set accessibility options for mouse gestures or keyboard control.
When you need, zoom the entire screen - which will include menus. Once you have finished with whatever system level task you are doing, simply zoom back down.
Remember that you can set the "view options" for system level windows, which currently allows you to increase the font to 16 and increase the size of the icons. If you are brave enough, there are also ways to modify the preferences through terminal to change this default size, but so far I have found none that will change the main menus.
For non-system windows, i.e., application windows such as browser pages or documents, you can zoom with a pinch (if you have a trackpad) or set the accessibility options you prefer.
If this is an issue for you, I highly recommend getting a trackpad, as I did for my father, because many gestures for zoom can be completed on the fly with little disruption to your usability.