New with Hashcat

[Alcanjp]

there is more than one answer to this

when using dictionary attack (as you are doing right now), you can combine your dictionary with rules, see
https://hashcat.net/wiki/doku.php?id=rule_based_attack

so in your case this would be a rule-file with just 2 rules
$X
$x

this tells hashcat to append one upper X or lower x to each pw-candidate you are trying

or when using mask-attack you can specify up to 4 different charset so

-1 Xx and mask ?a?a?a?a?1 means 4 times all possible chars, 5th char only X or x

EDIT:
Hashmode: 14600 - LUKS (Iterations: 163044)

Speed.#1.........:    3079 H/s (89.54ms) @ Accel:32 Loops:512 Thr:512 Vec:1
Speed.#2.........:    2833 H/s (44.74ms) @ Accel:8 Loops:1024 Thr:512 Vec:1
Speed.#5.........:      337 H/s (57.12ms) @ Accel:512 Loops:256 Thr:1 Vec:4
Speed.#*.........:    6249 H/s

not a real cracking rig, but luks is just slow...