None of my USB flash drives will fit into my Apple USBc adapter

Apple does sell a number of different USB-C adapters, so I'm not sure which one exactly you are referring to.

For example, if you have this one: https://www.apple.com/shop/product/MJ1M2AM/A/usb-c-to-usb-adapter?fnode=de6fa4fc9350b99f0caa66e4975a114980ebbbf5d1f79c7c6c44688157ba0a43a781111c78c93fbc9ee7745eb9e722d28e9ad702e10c41c2f96ab8bb29ad1e05d88224db6066fcca0e602c1cb077bf2d266e3d92648ce5db776875affaf1ff57005f372a4f42b57cd51ee3e47a7bacce3cdd2983f5483fd9fab256fd69758bba&fs=f%3Dadapter%26fh%3D43c51a%252B45b0

Then you should already have what you would need to connect an external USB drive (that uses a USB-A connector), to one of your Mac's USB-C ports.

Definitely, NO forcing should be required.

The smaller USB-C end of the adapter would plug into your Mac laptop. The other larger USB-A end would connect to the flash drive.

... but, let's get what is the exact make & models are of these flash drives.

For example, I use a number of external drives. They typically come with their own cables. If by "flash" drive, you are referring to a thumb drive, then these typically come with a built-in USB-A connector.

The following should give you an idea on the different types of USB connectors:

• https://www.cablestogo.com/learning/connector-guides/usb?utm_source=pardot&utm_medium=email&utm_campaign=leadgen-awareness&utm_content=usb-connector

... and these are some stock images of external USB drives:

• https://www.istockphoto.com/photos/external-hard-disk-drive

Sounds like your current USB flash drives use USB-A type connectors. In this case, it would be cheaper to just get a USB-C to USB-A adapter.

Something like the following: https://www.amazon.com/Syntech-Adapter-Thunderbolt-Compatible-MacBook/dp/B07CVX3516/ref=sr_1_3?sr=8-3