Is this possible to brute force?

[idop]

That keyspace is far too large for you to be able to bruteforce, even with the limited character set and at the lowest length of 12.

Edit: Some math for proofing

20 characters, 12 length, so 20^12 as total number of candidates, divided by a speed of roughly 2MH/s on a 3090 will give you approx 23703 days on 1x 3090. Or, 1 day on approx 23703x 3090. Each length longer than 12 increases this keyspace exponentially.

Understood, Thank you very much for the estimate too, very helpful.