Dotes is an extremely simple daily notes/journaling app partially inspired by rednotebook.
Start off by selecting where to store your journal. Then, every day you open the app, the day's entry is created and the time of opening is logged for you. From there, type whatever you'd like, and save with Command/Control + S, or from the menu bar. The app's preferences include switching between light and dark modes, a range of font size, and changing the location of the journal (note this does not move the existing journal).
Click the logo in the bottom right of the window to switch to viewing mode. This allows you to navigate (but not edit) past entries. Use the left and right arrow keys as shortcuts for the buttons, and Shift + [arrow key] for the first or latest entries.