I’m having trouble connecting the Apple first gen to my iPad 10 gen with lightning to usb-c.

Presumably you refer to a first generation Apple Pencil? To connect your Pencil to your iPad, you will require the USB-C to USB-C charging cable that was supplied with your iPad10 - and a special Lightning to USB-C adapter:

You should note that for pairing and charging from an iPad10, you cannot use a Lightning to USB-C cable and the older Lightning/Lightning adapter that was originally supplied with older first generation Apple Pencils.

New first generation Pencils now ship with the special Lightning/USB-C adapter in the box along with the Pencil. However, some older stock purchased from retailers may lack the USB-C to Lightning adapter - and may instead have an older Lightning to Lightning Adapter.

For owners of older first generation Pencils, or for “old stock” new Pencils, the new special adapter can be purchased directly from Apple as an accessory.

https://store.apple.com/uk/xc/product/MQLU3ZM/A

As such, if purchasing a new first generation Apple Pencil to accompany an iPad10, you might be best advised to visit an Apple Store or Apple Authorised Retailer that has a high-turnover of stock - and ensure that the Pencil box indicates that the correct adapter is included. 

If necessary, open the box in the Store and check that the USB-C/Lightning adapter is present - noting that the older Lightning/Lightning adapter looks very similar to the USB-C/Lightning adapter.

To be absolutely clear, you must use a USB-C/USB-C cable and matching special adapter to pair your Apple Pencil with - and charge the Pencil from - your iPad10.

While you can charge the Pencil from a Power Adapter using a USB to Lightning cable - together with the Lightning/Lightning Adapter that you have, this arrangement cannot be used to pair/charge with the iPad10.

It seems that something went awry with my last reply - as the first line was omitted…

Yes. You must use a USB-C/USB-C cable and matching special adapter.

Your iPad10 was supplied with both a USB-C to USB-C charging cable - and a 20W USB-C Power Adapter. If you don’t have these items, how do you charge your iPad?

If you have lost your USB-C/USB-C cable, it can be easily replaced:

• USB-C Charge Cable (1m)

https://store.apple.com/xc/product/MQKJ3ZM/A

USB-C cables are also available from good computer stores.

While USB-C cables all have the same physical connector, they are not necessarily wired the same. While many third-party USB-C cables will work without issue, in choosing an Apple cable, you have assurance that the cable will be the correct specification.