What parts what I need to put 26 inch rims and tires on my 24 inch bmx bike besides larger forks? Also what size are 700c forks in inches?

try visiting a bike shop, with your bike and ?asking there you may be wanting the impractical and too expensive..

#1 you will be changing the handling a lot. , may be cheaper to just buy a new bike.

A bigger frame, quite likely.

A custom-built wheel, possibly, to get a 26" wheel whose hub width matches your dropout spacing.

If you can get the wheel to fit, you may need some way to adapt brake reach.

700c rims have a bead seat diameter of 622 mm, which is the same as 29" mountain bike wheels.

For sake of comparison, 26" mountain bike rims have a 559 mm BSD. 24" BMX rims are 507 mm in diameter.

A whole new bicycle?

You can post a photo of your current frame and why you think it would work.

I've done 26" ==> 700c on one bike, going from a fat 26" tire to a narrow 700c tire, the wheel sizes worked out to be close enough to work. A fat 29" tire (same rim), would have been too much.

If you have rim brakes, consider how they will be affected by your change. In my 26" to 700c conversion, the V-Brake mounts were way too low. I used callipers instead. Disc brakes aren't affected by this.

Will_not_work.

"26" mountain bike rims have a 559 mm BSD. 24" BMX rims are 507 mm in diameter."

If you go with tires that are 26mm narrower than you currently have, the "26" " wheels will be the same outer diameter. For example if your current tires are 58-507, and you switch to 32-559 - everything except the brakes will not be an issue.....

BUT the 1st question is WHY ???? What do you intend to gain? Are you sure that you will gain something?

You have the bike, get out your calipers, tape measure, paper and pencil, and start measuring clearances between the tires and frame & fork; and brake pivots to rim.

It's a BMX
I'm guessing brake reach isn't a problem because it has none.

forks are in the neighborhood of 42cm

converted my son's 24" MTB for road:

www.bikeforums.net/g/picture/14131230

carbon fork, new crank/chainring, brake adapter, seatpost, stem, dropbar, 26" wheel from old mtb... about 480 all-in but better than any 1000 i've seen imo.