@Lachica I use Snapseed, mainly on my iPad, but there is a
version for Android which I have on my phone.
After installing it, the first thing to do is go to
Settings (via the three dots in the top right of the screen) and change
Image sizing from "do not resize" to "800px". (This change will be remembered for when you next use the app.) 800px is still a little larger than TSP can display but at least the file size will be a lot smaller.
Next you will need to open the photo you want to resize. This is done by tapping the
plus sign in the centre of the screen. You might need to navigate to where the photo is stored - this can be done via the three lines in the top left of the screen.
Once the photo is loaded, you can edit it (crop, tune image, etc) using the Tools option at the bottom of the screen. When any changes have been made, use the
Export option at the bottom of the screen to create a resized copy of the photo. I use "export" and this saves the new photo to the Snapseed folder, but if you want to choose where the copy is saved use the "export as" option instead.
As I said, I mainly used Snapseed on my iPad, but if you get stuck with the Android version I can try to help.