How to make a photo collage on MacOS Big Sur I print on an HP printer

What I did (in pages - I don't use word).

Select all the pictures - drag them all into pages (they will be selected in pages - but if they're not, ctrl-A will select them all).

Go the arrange tab and reduce the size to something manageable say around 5cm width (they will all reduce to the same width - so portrait format will be larger than landscape format, as you can see in my example - obviously if you want just select all portrait images and reduce the hight to match the landscape width)

Then you can go to the style tab and choose a style you like.

Then drag them around, or resize individual images by selecting and dragging the corners. You can also rotate individual images in the arrange tab

Hi

You can either get an app that will do it (perhaps from one of the photo printing sites) that plugs into photos. Or you can drag images from photos into pages and arrange them there.

Here is one I did in pages in about 1 minute. It might need a little more time to arrange the images more nicely, perhaps with some rotations - but you get the idea...

+1 on using Pages. I created this 96 picture 20" x 30" collage with it to have printed by a local printer: