App Icons
App Icons are the visual representation of a brand’s products, services or tools. Icons should communicate the core idea and intent of the product in a simple and friendly way.
Design Guidelines
Grid
When creating an app icon, use a grid of 192 x 192 dp (4:1), which will display edges at 4dp. When the scale is returned to 1:1, you must have a grid of 48 x 48 dp.
Grid 48 dp
Grid 192 dp
The icon grid establishes clear rules for the consistent, but flexible, positioning of graphic elements.
Alignment
App icons must be optically aligned to the center of the icon grid.
Correct alignment
Incorrect alignment
Container
App icons must be represented in a square shape with rounded borders. When designing you must include minimum padding based on 1/4 of the scaled icon grid size.
Resources
For a better approach, you should use the pack icon Special Flat from Flaticon. If the pack does not have the icon you are looking for, refer to the pack icon Basic Rounded Flat.
For view and download the pack icons please refer to the links Special Flat or Basic Rounded Flat
Then, to make the composition icon plus shape, you could use this web app: Launcher icon generator