It’s easy to select lines in visual mode, delete them, then paste them a few lines lower. However, this won’t adjust the indentation to match surrounding code.
Instead, add the following to your vimrc (or init.vim):
|  |  | 
Then select lines using visual mode (v or V) and press J or K to shift
them down or up one line, respectively. This will also adjust the indentation
properly (the same as pressing = while selecting the lines).