What is the screw size of s10e? And are they all the same size?

If you open up one of the iFixit repair guides related to the part you're trying to fix, you'll find that the iFixit crew takes the time to measure the length of the screws and put that number into the guide where the screw is removed. Unfortunately they don't measure the thread pitch and diameter, but at least the length is better than nothing.

As an example, I looked at the Motherboard Replacement guide. It appears that all of the screws holding the midframe and the speaker (about 15 altogether) are listed as being 3.9mm, so it does look like a lot of them are the same.

However, continuing on, there are also 3.7mm screws holding down the motherboard, so obviously the majority of the screws are the same, but not all.

If you need replacement screws, you can always get a set from places like eBay, Amazon and AliExpress; you may have to measure them to be sure you're putting the right one in, but it seems like there's not a lot of variety, so just be sure not to use a long one where a short one is supposed to go; many phones have been ruined by doing that.