DevKinsta has a default limitation on 128MB file upload.
In order to get that increased you will need to access shell.
It can be done by running
docker exec -it devkinsta_fpm bash
This will bring you to the terminal of the application server.
Depending on version of PHP you are using, file is located in
/etc/php/7.4/fpm/conf.d/tuning.ini
This is for version 7.4. If you need to edit file for different version you can simply change 7.4 in path with PHP version used.
3 values should be changed:
upload_max_size = 128M
post_max_size = 128M
upload_max_filesize = 128M
You can put 256M for all 3, restart DevKinsta, and you are done.