How can I insert the capital letter A in any cell without pressing on the button A on my keyboard or the screen keyboard?

The answer is :  =char(65)

because a small has decimal number97 and the capital A has decimal number65

and the formula char changes the decimal and convert it to binary then to ascii

You Can Click on Column A and go on "Name Box" where Shown A select by Mouse, Copy and Paste in any Cell

you can press the button ALT and then the number65

We can use insert symbol option to insert all characters.