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#11
A size of 128 Gb for an SSD should be more than enough. In my case W10 + many programmes + 11 Gb restore points amount to about 38 Gb on the SSD. This might temporary increase to 55 GB when an upgrade has taken place (windows.old still present).
A few cleaning possibilities are already mentioned. I would add that I disabled file history and windows search (they may occupy a lot of space). For searching much better/faster searching programmes are available (for instance I use Wise Jetsearch). Regularly I image the SSD (Macrium Reflect) and backup the data disk to an external disk. Don't forget to put on the system protection of the C disk. Standard it is set off by Windows, but it may help to recover unwanted changes on your C disk.