The Librem14 requires a DC input of at least 19V DC, so a type-C charge port regardless of Watt must be able to get up to 19V DC. I think most type-C supplies starting from 45W do 20V DC, which will work.
But please be a bit careful with type-C chargers. We had a lot of unpleasant surprises with type-C on the Librem5 and the Librem14 already. Type-C is complex and complicated and if it is not properly implemented on both sides then bad things can happen - wrong current/voltage gets negotiated, wrong timing etc.
So what I am trying to say, carefully test it, if something does not behave as expected then disconnect and do not try it again.
Cheers
nicole