Yes! If you'd like them to write the sentences neatly after they have constructed the sentence - write for them as they talk, then allow them time to copy an appropriate number of sentences neatly as a separate lesson.
Writing is a complex process. It involves many, separate skills - understanding content, reading, handwriting, spelling, touch typing, grammar and paragraph/essay structure. These skills don’t all come together until about age 12 for most children.
Until then, I encourage you to offer to write for your child whenever they are concentrating on learning a skill other than handwriting or spelling.