Well, there a lot of nuance here.
In the purest form as a solo miner you can calculate how long (on average) it would take you to find a block while using X hashrate. Then if you doubled your hashrate you would halve the time. You can play with numbers here: https://hashpower.braiins.com/solo-calculator
But if you are mining through a pool the the calculation is made based on your share of the total hastate of the pool. This way you don't have to wait for months or years to be paid.
And Doubling your hash in a pool will get you ~2x the share.
Now Difficulty only changes based in TOTAL hastate of the network AND only changes once every 2016 blocks.
So you changing your amount of hashrate *could* increase the difficulty in the FUTURE. But not necessarily. Because it's based on change on the whole network. You might go from 10 to 20 gigaboops while I go from 20 to 10. No net change.
But the network hastate does tend to increase over time which will naturally make blocks take longer to find, or your pool payout to decrease.
Clear as mud? 🤪🫎
