How much time to plan for clearing customs and flight transfer at Charles DeGaulle

According to this --https://easycdg.com/airport-guide/which-terminal-paris-cdg-airport-charlesdegaulle/

Air Canada uses 2A

KLM uses 2F

Check the airport map to see the degree of separation

Thanks. The link you sent is really helpful.

Unless airlines reduce the number of flights due to lack of demand, planes are flying lighter these days. You probably will have little wait to get through passport control, unless employee numbers are reduced. Three hours will be more than sufficient.

If you are on connecting flights with a single ticket, you have time.

If you are attempting to self connect through CDG, particularly if you are checking luggage, 3 hours is not sufficient time to guarantee your making a second flight.

should we plan on a four hours later flight?

As it appears you have a two ticket do it yourself transfer, the safer choice is 4 hrs. Especially if you have checked bags to deal with

three hours later is sufficient time to clear customs etc.,

it is the "etc." that takes the time, NOT customs. The "etc." is immigration, aka passport control. This can easily be 1 to 1½ hours.
Customs, which is the check on the contents of your luggage (anti-smuggling) happens after you pick up your bags, if they are checked through to Amsterdam, it will happen there, if you pick up your bags at Charles de Gaulle, it will happen there. But customs is a random stop only, 99% of the time you are not stopped so it takes zero time.

If this is one booking, 3 hours is OK.
If this is two separate bookings, you will have to pick up your bags at Charles de Gaulle and check in again for KLM, in which case 4 hours minimum.

Thank you all. This is very helpful. We're hoping not to check bags, but not 100% certain.