To quickly end a sentence with a period and a space, just double-tap the Space bar.
As you write, QuickType uses predictive text to anticipate your next word. Tap a word to choose it.
Accept a highlighted prediction by entering a space or punctuation.
Reject a suggestion by tapping your original word (shown as a QuickType option with quotation marks). Note: If you reject the same suggestion a few times, iPhone stops suggesting it. If you see a word underlined in red, tap it to see suggested corrections. If the word you want doesn't appear, type the correction.
To use speech-to-text, press the Microphone key, then speak the Desired phrase.
To copy text, double-tap a word, then move the selection handles to include the range of text you want to select. Then tap Copy.?
To paste, tap where you want to paste the text, then tap Paste.