Question: I’m playing a grappling Eldritch Knight, and wanted to know if advantage on Strength checks (from the [*enlarge/reduce*](https://www.dndbeyond.com/spells/enlarge-reduce) spell) would make my grapple check - which is an Athletics check - have advantage.

Answer: 
A Strength (Athletics) check is, in fact, a Strength check - the hint is in the word "Strength".

If you are initiating a [grapple](https://roll20.net/compendium/dnd5e/Combat#toc_42) then a Strength (Athletics) check is what you use and if you have advantage(disadvantage) on Strength checks you have advantage(disadvantage) on this check because, as pointed out above, its a Strength check.

If you are trying to avoid or escape from a grapple then you can choose to use Strength (Athletics) or Dexterity (Acrobatics). The first is a Strength check, the second isn't - its a Dexterity check. As a quick aside, Initiative is a Dexterity check so advantage(disadvantage) on Dexterity checks gives you the same on Initiative rolls.

If you are keen on building a grappler, you should check out the [Grappler's Guide](http://www.enworld.org/forum/showthread.php?468737-The-Grappler-s-Manual-(2-0)-Grappling-in-5th-Edition), one of the prime things it recommends aiming for is access to the *Enlarge* spell, partly to get the advantage you identified but also to allow you to grapple Huge sized creatures.
I believe so
------------

When you initiate a [grapple](https://www.dndbeyond.com/compendium/rules/basic-rules/combat#Grappling), you do so by:

> 
> ... making a grapple check instead of an attack roll: a **Strength (Athletics) check** contested by the target’s Strength (Athletics) 
> 
> 
> 

Meaning that advantage on Strength checks does give you advantage when trying to grapple.