When adding images to your slides, you can source them from Google Drive, upload them from your computer or search for images via Google Search. Once an image has been added, you can click on the image to manipulate it as required.
To add an image from Google Drive to a slide:
Click on the Insert menu, choose Image then Drive, or click on the drop-down arrow next to the image button on the toolbar and choose Drive
Locate the image you want to add - you can use the Recent, My Drive, Shared Drives and Shared with Me tabs to find images
Select the image, then click on Insert
To upload an image to a Google Slide from your computer:
Click on the Insert menu, choose Image then Upload from computer, or click on the drop-down arrow next to the image button on the toolbar and choose Upload from computer
Locate the image you want to add
Click on Open
You can also perform a Google search for images to add to a presentation.
Click on the Insert menu, choose Image, then Search the Web
Type your search text to find the images required
Press Return
Click on the image you wish to add to your slide
Click on Insert
You can click on the image to select it, then move or resize it as required.
Right-click over an image for all image formatting options including the Crop command. You can also use the Add to Theme command to add the image to all slides via the slide master.