The function CHAR(10) will return a Line Feed.
Combining with functions like CONCATENATE() or & will give a new line. Example:
=CONCATENATE("First line"; CHAR(10); "Second line")
="First line"&CHAR(10)&"Second line"
The only way that I found so far is through the clipboard.
Using a source document with a line break, with some effort you could succeed in selecting just the line break, and then copy/paste it.
Even easier is to use an app such as "Unicode Pad" or "Unicode CharMap", both of which will find and then copy/paste any character. You'll need to look for LF, ...
There may not be an exact solution to the problem as you posted it, but there are possible workarounds. Android's primary strength is it's customizability and modularity, so if one (your stock) keyboard does not satisfy you, you're welcome to switch it out for another which does.
I know of 3 keyboard apps off-hand that have a decimal point in their numeric ...
Unfortunately, you can't with the current version (1.19.432.04.34) of Google Sheet. Maybe it will be possible to do it with future version. For a once off (or maybe permanently), WPS allows to increase the width of frozen columns.
The highlight a throw-away character and hit enter trick, as well as the type everything into a text editor, then copy/paste it into the Google Sheets cell, both only work on Android devices. I have a Google Spreadsheet that I'm sharing with a client who has an iPhone, and she needs to be able to enter multiple lines within a cell. So I came up with just a ...
Mark the cell in which you want to have new lines.
At the top menu click the "A" next to the redo button.
in the lower screen section a modal pops up. There hit the tab "CELL".
Than activate "Wrap Text".
Now this cell will do line-breaks on long text.
It depends on the keyboard you are using. I tested it first with Gboard and secondly with Hacker's Keyboard and Microsoft SwiftKey Keyboard. With Gboard pressing Enter, insert a new line on the same cell. With Hacker's keyboard and Swiftkey, it takes you to the cell below. So, a possible solution is to use another keyboard (if GBoard is your default keyboard)...
In the support article Keyboard shortcuts for Google Sheets, the use of keyboard shortcuts is possible with an external keyboard.
From the article:
If you plug an external keyboard into your Android device, you can use the shortcuts below:
It goes on to enumerate the shortcuts.
You can enter them with Hacker's Keyboard.
While using Hacker's keyboard, ...
I first tried downloading Hacker's Keyboard because it gives you a full PC keyboard on your Android device. In other words, it has a Ctrl key. However, I could not get Ctrl+; to work. I could get other Ctrl+* combinations do their expected functions, but I believe there was an issue with context. The Android keyboard will only popup if you select a text ...
If you have a keyboard (bluetooth, tablet dock...), you can do:
Click the row number in the first column
Using shift + up or down arrow on the keyboard, select as many lines as you want to add at the end of the sheet
Click the row number of one of the selected lines, a menu should popup
Click 4th button ; a menu should popup with the following options: