No and yes.
First no: the ppi value does not matter for any operation that uses pixel measures. That is for all screen operation, including the web. A picture 1000x2000 pixels is the same, regardless if the ppi value us 72 or 300.
It matters, however, when you change to the printing world. PPI stands for Pixels Per Inch, so it translates the pixel values into a preferred inch value. I say preferred, as wirh modern DTP systems, you import the pixel file and scale the image to the size you need them. Programs like InDesign also use this value to generate the preview images for images linked in the design. So, if you set your PPI value to 72, the preview file will be huge, if you set it to something like 300 the preview file will be less big, setting it to 1200, the preview file will be tiny but the preview quality will be low. So yest, it matters here.
The output setting when you generate your print file also matters. If you generate an output for the screen, you normally set a low value, for keeping the file size low to be able to transfer the file via e-mail, or permit a fast download. But for standard professional print, you will set it to 300 ppi, as that is what the printer usually needs to produce high quality prints.
In Lightroom for export to JPEG, you can set that to 300 for a modern photo, and you will be good.
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