Currently set at 80mm but would like them out at 100mm, there pretty old maybe even first generation and they’re 29er version.
Is there a Poddy online guide, and do I need a little spacer?

I just gave them a service and removed the spacer I found inside.

Nothing required, remove the lowers and iirc there will be a few black spacers on one of the lower rods, just take one or two off.

Travel spacer limits the extension not the compression in order to lower the front on an 80mm travel. Otherwise you are just losing travel with no reduction in height. So they must be inside the air spring and its a bit more than just taking the lowers off.

So when I drop the lowers off the oil will come out? Or is there not much in there, a guide with photos would be very helpful…

Look for a reba service guide. Should be videos on you tube and documents on the sram site as well as forum guides.

You have a small quantity of lower leg oil in each side. This will need to be drained out and replaced – it is probably too low and dirty anyway.

You then need to remove the air spring piston (split ring on the bottom of the stanchion inside the fork) and the spacers are obvious on the shaft.

You will need to put a quantity of new oil in the air spring and then in each of the lower legs on assembly and are supposed to fit new crush washers. Really easy job but you will need some of the correct oil for lubrication.