Publishing other people's photos is bad. We have already dealt with this. However, if you do not have enough of your images, you can use free photo stocks.
Why don't you need to pay for stock images?
Most quality images are produced for sale. But photographers often publish their photos on stocks licensed under Creative Commons (CC) or Royalty Free (RF). It is these licenses that allow you to use the image for free.
Note that using photo banks, you need to be able to filter out irrelevant photos. If you work for Russia, the group of friends in the picture can hardly consist entirely of African Americans. And where in Moscow did you meet inscriptions in Spanish on the street?
But remember, the photo you will be using for the post may also be used by someone else. So try to add personality to her. For example, you can make a collage by cutting out the desired details from an image and placing them on a different background.
And, since it comes to that, we are sharing with you the photo stocks that we use ourselves: