You can change the attribute caps with a bit of modding. It normally isn't that big of a deal, with peasant level attributes on a human you can still get to very high stats without these, but I quite like having very high caps too. As a warning though, these will probably greatly imbalance fortress mode soldiers, and you as well because most people you encounter just have base level untrained stats, so being at 4,000 on every stat will make you on average 4 times as good as everybody else, just on an attribute level. That's probably enough to beat most enemies you encounter if you were dabbling in every skill.
Anyway, here's the code just copy and paste this into one of the creature files. To access them go to the dwarf fortress/objects/raw/creature_standard and look for whatever creature you want to play as. Just put it in the code anywhere that isn't interrupting other [THINGS_IN_BRACKETS_LIKE_THIS] and is past the name for the creature. It should work.
[PHYS_ATT_CAP_PERC:STRENGTH:400]
[PHYS_ATT_CAP_PERC:AGILITY:400]
[PHYS_ATT_CAP_PERC:TOUGHNESS:400]
[PHYS_ATT_CAP_PERC:ENDURANCE:400]
[PHYS_ATT_CAP_PERC:RECUPERATION:400]
[PHYS_ATT_CAP_PERC:DISEASE_RESISTANCE:400]
[MENT_ATT_CAP_PERC:ANALYTICAL_ABILITY:400]
[MENT_ATT_CAP_PERC:FOCUS:400]
[MENT_ATT_CAP_PERC:WILLPOWER:400]
[MENT_ATT_CAP_PERC:CREATIVITY:400]
[MENT_ATT_CAP_PERC:INTUITION:400]
[MENT_ATT_CAP_PERC:PATIENCE:400]
[MENT_ATT_CAP_PERC:MEMORY:400]
[MENT_ATT_CAP_PERC:LINGUISTIC_ABILITY:400]
[MENT_ATT_CAP_PERC:SPATIAL_SENSE:400]
[MENT_ATT_CAP_PERC:MUSICALITY:400]
[MENT_ATT_CAP_PERC:KINESTHETIC_SENSE:400]
[MENT_ATT_CAP_PERC:EMPATHY:400]
[MENT_ATT_CAP_PERC:SOCIAL_AWARENESS:400]