Dear heaven's this is dumb. I can get dropping stat penalties in some systems if they are to harsh but marking every race the same whats the point might as well drop it for a background system or a point system at that point.
The ability modifiers in 3E for half-orcs were flat broken, as they effectively lost 2 attribute points (+2 STR, -2 INT, -2 CHA) in exchange for being 'orc blooded' (counts as an orc for racial effects) and darkvision 60.
Hoo-fucking-ray.
Say what you will about Pathfinder 1E, but at least half-orcs weren't getting fucked in the ass statistically as compared to 3E. And while they got the generic '+2 to any one attribute', at least it came along with darkvision 60, +2 to intimidate checks, orc ferocity, and weapon proficiency with greataxes and falchions.
They actually explained in the 3e DMG in a section about adding new races that the designers felt Strength was more valuable than other stats and so, unless it was Dex, required a 2 for 1 tradeoff for Strength bonuses.
Worth remembering is that this decision was made back before there were many options to actually replace Strength with other stats for melee attacks and the only stat that added to weapon damage.
Not saying it was a great decision, but if you squint you can at least see the line of thinking.
My preference for dealing with size interacting with attributes is carry modifiers and weapon restrictions. A slower speed (shorter legs) and shorter jumping distance (in 3e all the small PC races had speeds of 20’ which also imposed a -8 to all jump checks) are also elements that can ensure that Strength scores are relative to size.
Sure, a kobold can have a 20 Strength, but its small so instead of being able to carry 200 lb., they can only carry 100 lb. (square-cube law says smaller things are proportionately stronger relative to their mass) and simple leverage means it can’t use a 3’ blade without using both hands and can’t use reach weapons at all. It also has to use its standard action for movement if it hopes to keep up with a human just using their move action and despite that 20 Strength its got a base -3 to its Jump check.
So a max strength kobold warrior is still weaker than a typical 12-13 Strength male laborer (10 is the average all humans, including women, sedentary males, the sickly and elderly) and it’s biggest two-handed sword strikes are doing 1d8+5 and even its spear attack can’t hit further than 5’ away while a 20 Strength human using a longspear is doing 1d10+7 at 10’ away (or 2d6+7 with a fullblade or greataxe at 5’).
But allowing that 20 Strength means that there’s a point to actually building a Kobold warrior because the melee hit and damage bonuses are still there for them.
By contrast, relying on no attribute bonus or even a penalty will probably skew things along the margins in more unrealistic ways. For example, even a -4 penalty to Strength would leave a Kobold who put their best score in Strength at a 14 and able to lift more than a typical human laborer, but it also utterly discourages any sort of kobold warrior build (unless finesse weapons are a thing) because that -4 is a big hit to their attack and damage rolls.
Raw size modifiers can more than sufficiently deal with differences in relative Strength way more realistically than just a -1 or even -4 to Strength could while still leaving concepts open and viable to fit certain campaigns (ex. a party of all halflings in a campaign where goblins, kobolds and similar small creatures are the common opponents would find strong -for halflings- warriors as viable as a halfling wizard, cleric or thief instead of them being unduly penalized in their core competency by only having a +2 while all the other classes have +5 to what they do best).
Basically, I think it’s more than possible to build a system where the racial traits provide for any physiological differences without actual modifying the default 3-18 at all. So instead of Orcs get +2 Strength, their carry capacity is instead 50% greater. Dwarves don’t get +2 Con, they get racial traits related to being exceptionally durable.