When you make a new Procreate file, you’ll be given the option to choose the size and resolution (DPI) of your canvas. You might want to choose a preset size such as A4, or you might prefer to choose a custom size.
If you want to print your artwork, you’ll want to use 300 DPI and as large a file size as possible, but be aware that this comes with limitations. Your maximum layers will vary depending on file size and DPI, so make sure you consider this before making your canvas.
You may also want to check your colour profile. For digital artwork, RGB is perfect, but if you want to print your artwork at a later date, you might want to use CMYK, as this is the colour setting that printers use.
You can also change the options for your time-lapse video, which is a video Procreate automatically creates showing the making of each of your drawings. You can set the size and quality of the video when making a new canvas.