Usually one step
A typical photo compresses under 100 KB with no visible change. You only need to resize if the image is very large or you need to go well below 100 KB.
For web pages
Also resize the photo to the width it will actually display at. A picture shown in an 800 px column does not need to be 4000 px wide.
Where 100 KB limits show up
Job portals, school and university forms, ID and KYC uploads, and many website builders limit images to around 100 KB. It's also a good target for photos on your own website, where smaller images make pages load faster on mobile.
JPG or PNG for 100 KB?
For photos, use JPG - it's designed for them and reaches 100 KB easily. PNG is better for screenshots, logos and text, but a PNG photo is usually several times larger. If you start with a PNG photo, convert it to JPG first.
A quick check
Open the compressed image next to the original at the same zoom. If you can't tell them apart, the compression level is right. If you see blocky edges around faces or text, compress a little less and reduce the dimensions instead.